CF related diabetes

1922 Banting FG, Best CH. Internal secretion of the pancreas. J Lab Clin Med 1922; VII: 251-266.
The work reported in this classic paper eventually led to a Nobel Prize in 1923 for Banting and Macleod, in whose Toronto laboratory the work was done. Frederick Banting (1891-1941) (figure 1) was a Canadian orthopaedic surgeon who became an assistant in physiology in Ontario where he worked in Richard McLeod’s laboratory with Charles Best, a medical student. It was here, after many ups and downs and arguments and with the help of Bertram Collip, a highly trained biochemist, to extract the insulin, that they eventually produced and tried the insulin on a diabetic patient in 1922.

The paper begins –“The hypothesis underlying this series of experiments was first formulated by one of us in November 1920 (Banting was then assistant in Physiology at Western University, London, Ontario) while reading an article dealing with the relation of the isles of Langerhans to diabetes (Barron M: The relation of the islets of Langerhans to diabetes with special reference to cases of pancreatic lithiasis. Surg Gynec Obstetr 1920; xxxi :437-448). From the passage in the article which gives a resume of degenerative changes in the acini of the pancreas following ligation of the ducts, the idea presented itself that since the acinous but not the island tissue degenerates after this operation, advantage might be taken of this fact to prepare an active extract of the islet tissue. The subsidiary hypothesis was that trypsinogen or its derivatives was antagonistic to the internal secretion of the gland. The failures of other investigators in this much worked field were thus accounted for”.

The authors concluded from their experiments that –“intravenous injections of extract from dog’s pancreas, removed from 7 to 10 weeks after ligation of the ducts, invariably exercises a reducing influence upon the percentage sugar of the blood and the amount of sugar excreted in the urine”

This medical classic is a “good read” and one of the most significant medical papers of the 20th century as also is Moses Barron’s paper that gave Banting the idea (above). It is included here not only for its historical interest but also for its relevance to CF as the majority of those affected will eventually develop CF related diabetes in adult life. Although the Islets of Langerhans in CF are functioning adequately through childhood in most patients, despite their severe exocrine pancreatic insufficiency, they are eventually destroyed resulting in the majority of adults with CF developing diabetes mellitus.

Efforts to prevent the slow destruction of the pancreas and prevent or delay the onset of CF related diabetes will surely become an area of research as more people survive to develop this complication which has an adverse effect both on their prognosis and quality of life.

1955 Shwachman H, Leubner H. Mucoviscidosis. Advan Pediat 1955; 7:249-323.[PubMed]
The paper contains the first detailed report of symptomatic diabetes mellitus and CF in a white boy aged 5 years from Kaloa, Hawaii – considered to be the superimposition of one serious disease on another.

The authors note that “mucoviscidosis is so well established today that we seldom see individual case reports except in areas where interest in the disease is awakening (for example South Africa, Canada and Germany). Rather we look forward to monographs such as Bodian’s (1952 above) and May’s (May CD. Cystic fibrosis of the pancreas in infants and children. Springfield Ill: Charles C Thomas. Publisher, 1954 above) where accumulated experience is recorded”.
They note that in Bodian’s book Cedric Carter, the geneticist, combined the data from Andersen and Hodges, Lowe, May and Reed with his own to confirm the expected probability of 1 in 4 children being affected. The importance of di Sant’Agnese’s recent (1953) description of the sweat electrolyte abnormality is mentioned particularly its importance in the recognition of the 5 – 10% of people with CF without clinical pancreatic insufficiency – but the tryptic activity of duodenal juice was still of great importance in diagnosis. Shwachman describes their experience of inducing sweating in 300 children by placing the child in a plastic suit bag for 30-90 minutes with pieces of covered gauze on the back. Values of over 80 meq/l were considered diagnostic of cystic fibrosis.
The beneficial effect of controlling infection with antibiotics in contrast to the relatively unsuccessful attempts with various inhalations including trypsin and oral iodides was stressed – “early recognition of the disease and prompt antibiotic therapy may be so encouraging that parents as well as doctor begin to question the original diagnosis”!
Finally, Shwachman notes that the average age of death from 1940-48 was 12.8 months and from 1949-53 was 45.2 months – the broad spectrum antibiotics came into use in 1949 and were considered likely to be one of the reasons for the improvement.

This 74 page paper, with 142 references, is a very detailed review of the current knowledge of CF up to that time by Harry Shwachman, written with the assistance of Hugo Leubner of the WHO and Pincus Catzel, then a research fellow; it makes very interesting reading.

1961 Huhnstock K, Schwarz G. On mucoviscidosis in adults and diabetes mellitus. Klinische Wochenschrift 1961; 39:854-7. [PubMed]
These authors screened 250 adults with diabetes mellitus using Shwachman plates (Shwachman et al, 1956. above) and those who were positive had sweat tests performed by the bag method. Nine of the 250 diabetic adults had positive sweat tests but no other signs of cystic fibrosis.

These findings are difficult to explain as diabetes mellitus is usually a late feature in the progression of cystic fibrosis. Also the ages of the patients (between 49 and 66 years) were quite against the individuals having cystic fibrosis. It is difficult to accept these findings particularly as there were no other signs of cystic fibrosis in these middle aged patients. Also a number of authors had found some apparently healthy adults with sweat tests with values of sodium and chloride over 60 meq/l.

This paper was followed by a number of publications on the relationship between established diabetics and cystic fibrosis.

–   The first description of diabetes mellitus in cystic fibrosis is usually attributed to Shwachman & Leubner, 1955 (reviewed above).

1962 Rosan RC, Shwachman H, Kulczycki LI. Diabetes mellitus and cystic fibrosis of the pancreas. Laboratory and clinical observations. Am J Dis Child 1962; 104:625-34. [PubMed]
One of the early descriptions of diabetes mellitus in cystic fibrosis; the first was in 1955 by Shwachman & Leubner (above). In the present paper 10 patients with diabetes mellitus were identified in a CF population of about 1300 patients seen since 1947 – one adult, three teenagers and the rest children. Reviewing the 10 patients – eight required insulin therapy, they noted that diabetes complicates management but does not necessarily shorten survival; it may begin at any age; four of the 10 patients were mentally retarded – an unusual occurrence in CF which was not discussed in the paper; the complication was indistinguishable from juvenile diabetes except ketosis was very rare; all were pancreatic insufficient.

The authors predicted that subclinical diabetes must exist in a large proportion of people with CF. This prophetic observation was absolutely correct but was a new concept at the time when there were very few adults with cystic fibrosis. There were so few patients with diabetes mellitus and CF that this paper reporting 10 patients was published.

1969 Milner AD. Blood glucose and serum insulin levels in children with cystic fibrosis. Arch Dis Child 1969; 44:351-355. [PubMed]
One of the early studies on glucose metabolism from Great Ormond Street, London by Tony Milner at a time when few patients survived to an age when they developed diabetes. However, it had been predicted that this might occur as patients became older. Glucose and insulin levels were measured after oral glucose and intravenous glucose, glucagon and tolbutamide in 61 children with CF. The results suggested that the increased incidence of impaired glucose tolerance was due to a defect in the release of an glucagon-like substance from the alimentary system in addition to defective islet cell function. (also Rosan et al, 1962 above; Huhnstock K & Schwarz G, 1961 above)

1992 Lanng S, Thorsteisson B, Nerup J, Koch C. Influence of the development of diabetes mellitus on the clinical status in patients with cystic fibrosis. Eur J Paediatr 1992; 151:684-687. [PubMed]
The first of a series of papers about CF related diabetes (CFRD) from Copenhagen and other centres. The new and important message from this paper being that diabetes mellitus adversely affects progress for some time before it becomes clinically obvious. When diabetes develops in CF patients, an insidious decline in overall clinical status is observed for some years prior to its clinical diagnosis. Whether clinical deterioration in CF leads to DM, or pre-diabetes results in declining CF clinical status is unclear. Accumulating evidence suggests that the latter may be the case since insulin therapy seems to improve lung function in cystic fibrosis.

–   This important Danish study encouraged the introduction of the policy of searching for glucose intolerance when patients of 12 years and older were seen for their Annual Review – a policy agreed by most, but not all, CF physicians.

2000 Moran A. Cystic fibrosis-related diabetes: an approach to diagnosis and management. [PubMed]
The Cystic Fibrosis Foundation held a consensus conference in 1998 to define the current standards for the diagnosis and care of CF related diabetes (Moran A, Hardin D, Rodman D et al. Diagnosis, screening, and management of CFRD: a consensus conference report. J Diabetes Res Clin Pract 1999: 45: 61-73). This article reviews those recommendations, and presents the practical approach to the management of CFRD used at the University of Minnesota.

The CF Foundation recommendations were recently reviewed again (Moran A. Updates on CFRD guidelines. Pediatr Pulmonol 2009; Suppl 32:208-209. S19.4). There was a further CFF Consensus Conference on CFRD in Sept. 2009.

2004  The UK CF Trust consensus document Management of Cystic Fibrosis Related Diabetes Mellitus by the CF Trust’s Diabetes Working Group was published in 2004 and is available on the website (www.cftrust.org.uk).

2004 Starkman H, Das S. Cystic fibrosis presenting as new onset diabetes mellitus in adolescent twins. Pediatr Diabet 2004; 5:99-101. [PubMed]
Identical adolescent twin girls presented with symptoms consistent with type 1 diabetes. Medical work up for evaluation of gastrointestinal symptoms led to a diagnosis of cystic fibrosis (CF) in both. These cases suggest that diabetes can be a presenting symptom of CF in the absence of pulmonary symptomatology.

–   This is the first report of such a presentation of CF. In 1961 Huhnstock K, Schwarz G reporting on mucoviscidosis in adults and diabetes mellitus [PubMed] (above) screened 250 adults with diabetes mellitus using Shwachman plates and those who were positive had sweat tests performed by the bag method. Nine of the 250 diabetic adults had positive sweat tests but no other signs of cystic fibrosis. It seems most unlikely that they had CF.

2006 Andersen HU, Lanng S, Pressler T, Laugesen CS, Mathiesen ER. Cystic fibrosis-related diabetes: the presence of microvascular diabetes complications. Diabetes Care 2006; 29:2660-3.[PubMed]
Thirty-eight patients aged 30 years (range 18-55yrs) with CF-related diabetes for 20 years (0-31yrs) were screened for diabetes complications at the Copenhagen CF Centre. Because of chronic pulmonary infections, the majority of patients were regularly treated with aminoglycoside and cyclosporine was given to those who had lung transplants. Since the pharmacological treatment of lung transplant patients could influence metabolic regulation and renal function, the results were given separately for nontransplanted (n = 29) and transplanted (n = 9) CF patients.
Nine of these diabetic patients (27%) had retinopathy, two of whom had proliferative retinopathy requiring laser treatment. Lung transplantation did not affect the prevalence of retinopathy. In 29 non-transplanted patients, nine had hypertension, three microalbuminuria, and one elevated creatinine; none had macroalbuminuria. In transplanted patients (9), eight had hypertension, two had microalbuminuria, and none had macroalbuminuria; seven of the nine had elevated plasma creatinine, and severely reduced glomerular filtration rate was significantly more frequent.

–   So a high frequency of diabetic retinopathy was found in patients with insulin-treated CF-related diabetes, stressing the need for a regular screening program as in type 1 diabetes. Severely impaired kidney function was common in lung transplant patients, probably secondary to cyclosporine treatment but many would also have had life long regular courses of intravenous aminoglycosides. As age increases so do complications. Eventually the majority of older people with CF will develop diabetes and it is clear that eventually many will develop diabetic complications particularly retinopathy. The added complications associated with immunosuppressant drugs in those who have had lung transplants and the effects of repeated courses of aminoglycosides contribute to the high frequency of renal complications.

2007 Schwarzenberg SJ, Thomas W, Olsen TW, Grover T, Walk D, Milla C, Moran A. Microvascular complications in cystic fibrosis-related diabetes. Diabetes Care 2007; 30:1056-1061. [PubMed]
The incidence of cystic fibrosis-related diabetes (CFRD) and the prevalence of diabetic microvascular complications were determined at the University of Minnesota. During 1990-2005, 775 patients aged 6 years and older were followed. CFRD was diagnosed in 285 subjects (52% female), 64% of whom had fasting hyperglycaemia. No subject with CFRD without fasting hyperglycaemia had retinopathy or abnormal urine albumin/creatinine ratio. In CFRD subjects with fasting hyperglycaemia and diabetes for 10 years or longer, 14% had microalbuminuria and 16% had retinopathy. Autonomic neuropathy and gastrointestinal symptoms each were seen in 52% and somatic abnormalities in 22% of patients with or without fasting hyperglycaemia.
The authors concluded that diabetic microvascular complications occur in CFRD, although the prevalence of retinopathy and nephropathy appears to be less than that found in other forms of diabetes. They advised that annual complication screening should occur after known diabetes duration of 5 years in patients with CFRD with fasting hyperglycaemia.

–   It is likely that CFRD will prove to be an increasingly important complication as the age of the adult CF population increases as will its complications as described here (Also Andersen HU et al, 2006 above).

2007 Battezzati A, Battezzati PM, Costantini D, Seia M, Zazzeron L, Russo MC, Dacco V, Bertoli S, Crosignani A, Colombo C. Spontaneous hypoglycaemia in patients with cystic fibrosis. Euro J Endocrinol 2007; 156:369-376. [PubMed]
A total of 129 CF patients without stable diabetes received 188 oral glucose tolerance tests. Fasting plasma glucose of < 60 mg/dl (3.3 mmo/l) was detected in 14% of studies and reactive hypoglycaemia (PG < 50 mg/dl (2.8 mmo/l)) in 15%. The oral glucose tolerance test-based diabetes frequency was similar in the lowest quartile (Q1) and Q2-3 for fasting plasma glucose (10 and 8%), with higher glucose increment and area under the curve in Q1. Insulin and C-peptide levels were similar among fasting plasma glucose (FPG) quartiles. Those with class I CFTR mutations had higher insulin concentrations than class II, especially in Q1 for FPG. Lower FPG was associated with more frequent hospitalization rates and lower Shwachman scores.

Fasting asymptomatic hypoglycaemia is frequent and possibly related to inappropriate insulin secretion control in class I mutation carriers. Low fasting plasma glucose does not exclude impaired glucose tolerance and diabetes in CF and does reflect worse clinical status.

2008 van den Berg JM, Morton AM, Kok SW, Pijl H, Conway SP, Heijerman HG. Microvascular complications in patients with cystic fibrosis-related diabetes (CFRD). J Cyst Fibros 2008; 7:515-519. [PubMed]
79 patients with CFRD were matched with 79 patients with DM1 according to sex, age and duration of insulin therapy. Retinopathy, peripheral neuropathy, nephropathy and microalbuminuria were the microvascular complications assessed. Risk factors studied were: smoking, BMI, HbA1c, cholesterol, cholesterol/HDL ratio, diastolic and systolic blood pressure. Both groups had the same number of microvascular complications (29%). CFRD patients showed more microalbuminuria (21% versus 4.1%; p=0.003), while retinopathy was more common in patients with DM1 (24% versus 10%; p=0.044). The prevalences of peripheral neuropathy and nephropathy were similar. Patients with CFRD had lower BMI (p<0.0001), total cholesterol (p<0.0001) and HbA1c (p=0.056) levels, and a lower prevalence of smokers (p<0.0001). Cholesterol/HDL ratio and diastolic and systolic blood pressure were similar in both groups.

The microvascular complications shown by patients with CFRD are similar to those seen in patients with DM1 but with a lower prevalence of retinopathy and a higher prevalence of microalbuminuria. The latter may reflect the influence of other cystic fibrosis-related factors on renal function.

2009 Moran A, Dunitz J, Nathan B, Saeed A, Holme B, Thomas W. Cystic fibrosis-related diabetes: current trends in prevalence, incidence, and mortality. Diabetes Care 2009; 32:1626-1631. [PubMed]
Cystic fibrosis (CF)-related diabetes (CFRD) diagnosis and management have considerably changed since diabetes was first shown to be associated with a poor prognosis in subjects with CF. Current trends in CFRD prevalence, incidence, and mortality were determined from a comprehensive clinical database.

Data were reviewed from 872 CF patients followed at the University of Minnesota during three consecutive intervals: 1992-1997, 1998-2002, and 2003-2008. CFRD is currently present in 2% of children, 19% of adolescents, and 40-50% of adults. Incidence and prevalence are higher in female subjects aged 30-39 years; otherwise, there are no sex differences. In younger individuals, CFRD without fasting hyperglycemia predominates, but fasting hyperglycemia prevalence rises with age. CFRD mortality has significantly decreased over time. From 1992-1997 to 2003-2008, mortality rate in female subjects dropped by >50% from 6.9 to 3.2 deaths per 100 patient-years and in male subjects from 6.5 to 3.8 deaths per 100 patient-years. There is no longer a sex difference in mortality. Diabetes was previously diagnosed as a perimorbid event in nearly 20% of patients, but of 61 patients diagnosed with diabetes during 2003-2008, only 2 died. Lung function but not nutritional status is still worse in CF patients with diabetes compared with those without diabetes. Nutritional status and pulmonary status are similar between patients without fasting hyperglycemia and those with fasting hyperglycemia.
Previously noted sex differences in mortality have disappeared, and the gap in mortality between CF patients with and without diabetes has considerably narrowed.

The auhtors believe that early diagnosis and aggressive treatment have played a major role in improving survival in these patients.

–   A useful review of changes in the features of CFRD by Antoinette Moran an expert on CFRD from Minnesota.

2009 Moran A, Pekow P, Grover P, Zorn M, Slovis B, Pilewski J, Tullis E, Liou TG, Allen H. Cystic Fibrosis Related Diabetes Therapy Study Group. Insulin therapy to improve BMI in cystic fibrosis-related diabetes without fasting hyperglycemia: results of the cystic fibrosis related diabetes therapy trial. Diabetes Care 2009; 32:1783-1788. [PubMed] Cystic fibrosis-related diabetes (CFRD) without fasting hyperglycemia (CFRD FH-) is not associated with microvascular or macrovascular complications, leading to controversy about the need for treatment.

The Cystic Fibrosis Related Diabetes Therapy (CFRDT) Trial sought to determine whether diabetes therapy improves BMI in these patients. A three-arm multicenter randomized trial compared 1 year of therapy with premeal insulin as part, repaglinide, or oral placebo in subjects with cystic fibrosis who had abnormal glucose tolerance. One hundred adult patients were enrolled. Eighty-one completed the study, including 61 with CFRD FH- and 20 with severely impaired glucose tolerance (IGT).

During the year before therapy, BMI declined in all groups. Among the group with CFRD FH-, insulin-treated patients lost 0.30 +/- 0.21 BMI units the year before therapy. After 1 year of insulin therapy, this pattern reversed, and they gained 0.39 +/- 21 BMI units (P = 0.02). No significant change in the rate of BMI decline was seen in placebo-treated patients (P = 0.45). Repaglinide-treated patients had an initial significant BMI gain (0.53 +/- 0.19 BMI units, P = 0.01), but this effect was not sustained. After 6 months of therapy they lost weight so that by 12 months there was no difference in the rate of BMI change during the study year compared with the year before (P = 0.33). Among patients with IGT, neither insulin nor repaglinide affected the rate of BMI decline. No significant differences were seen in the rate of lung function decline or the number of hospitalizations in any group.

The authors concluded that insulin therapy safely reversed chronic weight loss in patients with CFRD FH-.

A conclusive result showing that insulin improves the nutritional state of people with CF who have impaired glucose tolerance without fasting hyperglycaemia.

Two more recent reviews on CF related diabetes mellitus, not included in main text, are as follows –

2010  Stecenko AA, Moran A. Update on cystic fibrosis-related diabetes. Curr Opin Pulm Med. 2010 Nov;16(6):611-5. doi: 10.1097/MCP.0b013e32833e8700. [PubMed]
The aim of this articis to provide a detailed review of recent publications on cystic fibrosis-related diabetes (CFRD) with a particular focus on the interplay between cystic fibrosis (CF) lung disease and diabetes.  CFRD is a form of diabetes that is distinct from type 1 or type 2 diabetes. CFRD remains very common and increases in prevalence with increasing age so that one in two middle-aged CF persons have CFRD. People with CFRD have lower lung function, worse nutrition, more frequent hospitalization, and worse mortality than CF people without diabetes. The excess mortality previously noted in women with CFRD compared with CF women without diabetes or CF men is much less apparent. CFRD is due to insulin deficiency and peripheral insulin resistance is much less a factor. Genetic susceptibility and oxidant stress are key risk factors for developing CFRD. The lung is the prime end organ target in CFRD and mortality is due to respiratory failure, not vascular complications. Insulin is the mainstay of therapy and early recognition and institution of therapy appear to improve health outcomes.
CFRD remains one of the most important co-morbidities in CF. Early recognition of the disease and therapeutic intervention may diminish the negative impact that diabetes has on lung health in CF. Although a clearer understanding of the role of oxidant stress and genetics in the pathogenesis of CFRD is being elucidated, much needs to be learned before more targeted, specific therapies can be developed for this distinct form of diabetes.

*2010 Laguna TA, Nathan BM, Moran A. Managing diabetes in cystic fibrosis. Diabetes Obes Metab 2010; 12:858-64. [PubMed]
Cystic fibrosis related diabetes (CFRD) is the most common co-morbidity in persons with cystic fibrosis (CF). As the life expectancy of persons with CF continues to increase, the need to proactively diagnose and aggressively treat CFRD and its potential complications has become more apparent. CFRD negatively impacts lung function, growth and mortality, making its diagnosis and management crucial in a population already at high risk for early mortality. Compared to type 1 and type 2 diabetes, CFRD is a unique entity, requiring a thorough understanding of its unique pathophysiology to facilitate the creation and utilization of an effective medical treatment plan. The physiology of CFRD is complex, likely consisting of a combination of insulin deficiency, insulin resistance and a genetic predisposition towards the development of diabetes. However, the hallmark of CFRD is insulin deficiency, necessitating the use of exogenous insulin as the mainstay of therapy. Insulin administration, in combination with a multidisciplinary team of health professionals with expertise in the care of patients with CF and CFRD, is the cornerstone of the care for these patients. The goals of treatment of the CFRD population are to reverse protein catabolism, maintain a healthy weight, and reduce acute and chronic diabetes complications. Creating a partnership between the treatment team and the patient is the ideal way to accomplish these goals and is essential for successful diabetes care.

2010 Rogan MP, Reznikov LR, Pezzulo AA, Gansemer ND, Samuel M, Prather RS, Zabner J, Fredericks DC, McCray PB Jr, Welsh MJ, Stoltz DA. Pigs and humans with cystic fibrosis have reduced insulin-like growth factor 1 (IGF1) levels at birth. Proc Nat Acad Sci 2010; 107:20571-5. [PubMed]
People with cystic fibrosis (CF) exhibit growth defects. That observation has been attributed, in part, to decreased insulin-like growth factor 1 (IGF1) levels, and the reduction has been attributed to malnutrition and pulmonary inflammation. However, patients with CF already have a reduced weight at birth, a manifestation not likely to be secondary to poor intrauterine nutrition or inflammation. Also CF pigs were smaller than their non-CF littermates and had lower IGF1 levels. To better understand the basis of IGF1 reduction, the authors studied newborn CF pigs and found low IGF1 levels within 12 hours of birth. Moreover, humerus length and bone mineral content were decreased, consistent with less IGF1 activity in utero. These findings led them to test newborn humans with CF, and they found that they also had reduced IGF1 levels. Discovering lower IGF1 levels in newborn pigs and humans indicates that the decrease is not solely a consequence of malnutrition or pulmonary inflammation and that loss of cystic fibrosis transmembrane conductance regulator function has a more direct effect. Consistent with this hypothesis, they discovered reduced growth hormone release in organotypic pituitary slice cultures of newborn CF pigs. These findings may explain the long-standing observation that CF newborns are smaller than non-CF babies and why some patients with good clinical status fail to reach their growth potential. The results also suggest that measuring IGF1 levels might be of value as a biomarker to predict disease severity or the response to therapeutics. Finally, they raise the possibility that IGF1 supplementation beginning in infancy might be beneficial in CF.

These very interesting findings do suggest a possible explanation the suboptimal growth of some CF infants despite optimal treatment and a good clinical condition. Also they provide a very plausible explanation for the well documented reduced birth weight of CF infants as a group.

Various studies have shown that growth hormone has some value in improving growth of CF children (see TOPICS – ENDOCRINOLOGY) but as yet IGF-1 supplementation has not been reported although the relationship of growth and IGF-1 has been described in CF (Switzer M, Rice J, Rice M, Hardin DS. Insulin-like growth factor-I levels predict weight, height and protein catabolism in children and adolescents with cystic fibrosis. J Pediatr Endocrinol 2009; 22:417-424.[PubMed]).

2011 Haupt ME, Kim EE, Prestridge AL. Successful prolonged use of recombinant human insulin-like growth factor-1 in a child with cystic fibrosis. Pediatr Pulmonol 2011; 46:1137-41. [PubMed]
These authors report the successful prolonged use of recombinant human insulin-like growth factor-1 in an adolescent boy with CF, who demonstrated significant clinical benefits from the therapy.

–   Growth failure is a common and complicated process in children with cystic fibrosis. Growth hormone, which is becoming a more commonly used agent in such patients, has demonstrated beneficial effects aside from increased growth velocity. Recently, insulin-like growth factor-1 has gained significant attention in the understanding of growth failure in children with CF. This present report is the first of its use in a child with CF.

2011 Rana M, Munns CF, Selvadurai HC, Simonds S, Cooper PJ, Woodhead HJ, Hameed S, Verge CF, Lafferty AR, Crock PA, Craig ME. Increased detection of cystic-fibrosis-related diabetes in Australia.  Arch Dis Child 2011; 96:823-826.[PubMed]
To estimate the incidence of cystic-fibrosis-related diabetes (CFRD) in youth from New South Wales (NSW) and the Australian Capital Territory (ACT), Australia and to examine demographic/clinical features at diagnosis.  Incident cases of CFRD in young people aged <= 18 years diagnosed during 2000 to 2008 were identified from four paediatric cystic fibrosis (CF) clinics and the NSW/ACT Australasian Paediatric Endocrine Group Diabetes Register.  CFRD was diagnosed in 41 cases (59% girls). The estimated mean annual incidence of CFRD among patients with CF was 9.4 per 1000 person years (95% CI 6.8 to 12.8). Incidence increased from 2.0 per 1000 person years in 2000 to 22.1 per 1000 in 2008 (incidence RR 1.3, 95% CI 1.1 to 1.4). Haemoglobin A1c (HbA1c) was abnormal in the majority at diagnosis: median HbA1c was 6.9% (6.2-8.1%). More cases were diagnosed using an oral glucose tolerance test in 2007-2008 compared with previous years (61% vs 6%, p<0.001).   CFRD is increasingly recognised and now affects approximately one in five young people with CF. The rising incidence is likely to be due to increased detection, resulting from greater awareness and changes in screening practices. Widespread uptake of consensus guidelines for screening will ensure accurate case detection, but will also impact on patient care and resource allocation.

–   As CF has becomes a condition of older people so the complications have become an increasing problem none less than diabetes mellitus. Although there is adequate insulin produced by the damaged pancreas for most children, as destruction of the pancreas continues diabetes develops in the majority. It is unfortunate that the destruction of the pancreas cannot be halted to preserve the islet cells for further destruction. Perhaps the systemic effect of the mutation specific drugs such as Kalydeco will have a favourable effect on halting the destruction of the pancreas and preserving the islet cells – already some evidnec that this may occur (Bellin et al. 2013. below)

2012 Waugh N, Royle P, Craigie I, Ho V, Pandit L, Ewings P, Adler A, Helms P, Sheldon C. Screening for cystic fibrosis related diabetes : a systematic review. Health Technology Assessment (Winchester, England) 2012; 16(24):iii-iv, 1-179.  [PubMed]
The initial aim was to review the methods for screening for CFRD, which can be symptomless but still be causing harm. As the aim of screening and early detection is to allow earlier treatment, a second aim was to assess the effectiveness of treatments. However, during the review it became clear that there were problems with how CFRD is defined, uncertainty about when hyperglycaemia should be treated. Details of relevant studies were obtained from the usual bibliometric databases. Diabetes is usually defined based on the level of blood glucose (BG) at which the risk of retinopathy occurs. For CFRD, it would be better to define it on the level at which the risk of lung disease (pulmonopathy) rises. There seems little place for treatments other than insulin, but the best insulin regimen remains to be confirmed. The best screening test may be by continuous glucose monitoring systems but further evidence is required. Screening may need to detect BG levels of > 8 mmol/l because that may be the level above which pulmonopathy starts in people with CF.

The evidence base for treatment is disappointing with few large randomised controlled trials. The key question is when treatment should start, perhaps at the post-prandial hyperglycaemia stage. Research is needed. Until that is done, we cannot be sure what we are screening for, and, therefore, which screening strategy should be used.

The definition of CFRD should probably be based on pulmonopathy risk, rather than using the classical definition of diabetes. That implies that we should be screening for a wider range of hyperglycaemia than in other forms of diabetes, perhaps to detect BG excursions of > 8 mmol/l. Insulin treatment may need to start at lower levels than formerly accepted.

This HTA document contains a vast amount of up to date information and over 250 previous references regarding CF related diabetes.

2013 Bellin MD. Laguna T. Leschyshyn J. Regelmann W. Dunitz J. Billings J. Moran A. Insulin secretion improves in cystic fibrosis following ivacaftor correction of CFTR: a small pilot study. Pediatr Diabetes 2013; 14:417-421. [PubMed]
An open-label pilot study in CF patients with the G551D mutation given new prescriptions for ivacaftor. At baseline and 4wk after daily ivacaftor therapy, intravenous glucose tolerance tests (IVGTT) and oral glucose tolerance tests (OGTT) were performed.

Five patients aged 6-52 were studied. After 1month on ivacaftor, the insulin response to oral glucose improved by 66-178% in all subjects except one with long-standing diabetes. OGTT glucose levels were not lower in the two individuals with diabetes or the two with normal glucose tolerance (NGT), but the glucose tolerance category in the subject with impaired glucose tolerance (IGT) improved to NGT after treatment. In response to intravenous glucose, the only patient whose acute insulin secretion did not improve had newly diagnosed, untreated CFRD. The others improved by 51-346%. Acute insulin secretion was partially restored in two subjects with no measurable acute insulin response at baseline, including the one with IGT and the one with long-standing diabetes.

The authors concluded the results suggest there is a direct role of CFTR in human insulin secretion. Larger, long-term longitudinal studies are necessary to determine whether early initiation of CFTR correction, particularly in young children with CF who have not yet lost considerable beta-cell mass, will delay or prevent development of diabetes.

These are really exciting results. The prevention of CF realted diabetes would represented a major advance in improving the health and quality of life of many people with CF.

2013 Kelly A. Moran A. Update on cystic fibrosis-related diabetes. J Cyst Fibros 2013; 12:318-31. [PubMed]
This paper will review the 2010 U.S. and other international guidelines for screening and treating CFRD. It will highlight newer data regarding early glucose and insulin secretion defects, mechanisms linking CFRD to worse outcomes, and recent advances in T2DM that may provide insights for CFRD; insulin secretion will be reviewed as background for these recent developments.

A detailed review of the present situation regarding the recognition and management of CFRD by recognised experts in the condition.

2013 Bridges N. Diabetes in cystic fibrosis. Paediatric Respiratory Reviews 2013; 14 Suppl 1:16-8. [PubMed
Cystic fibrosis related diabetes (CFRD) is a common complication of cystic fibrosis, caused by a fall in insulin secretion with age in individuals with pancreatic insufficiency. CFRD is associated with worse clinical status and increased mortality. Treatment of CFRD with insulin results in sustained improvements in lung function and nutrition. While clinical experience with insulin treatment in CF has increased, the selection of who to treat and glycaemic targets remain unclear.

Dr Nicola Bridges is paediatric endocrinologist and Service Director for paediatric medical specialities at the Chelsea and Westminster Hospital, London. She provides endocrinological expertise for the children attending the paediatric CF clinic at the Royal Brompton Hospital, London.

2013 Kopp BT. Kirkby S. Hayes D Jr. Flanigan KM. Diabetic myonecrosis in a cystic fibrosis patient. Resp Care 2013; 58:e123-5.[PubMed]
The authors report the case of a 32-year-old with poorly controlled diabetes presenting with sub-acute leg pain and focal quadriceps tenderness. Neuromuscular testing and extensive workup revealed diabetic myonecrosis. To the authors’ knowledge, this is the first reported case of diabetic myonecrosis in a patient with CF, and highlights the need for pulmonary physicians to recognize this diabetic complication in CF patients, which is associated with a poor long-term prognosis and existing microvascular complications.

20014 Middleton PG. Wagenaar M. Matson AG. Craig ME. Holmes-Walker DJ. Katz T. Hameed S. Australian standards of care for cystic fibrosis related diabetes. Respirology 2014; 19:185-92.  [PubMed]
This document seeks to combine various guidelines to provide an Australian approach to the management of CFRD and establish the guidelines within the Australian CF Standards of Care. It is intended that this document will provide assistance to doctors, nurses, dietitians, physiotherapists, diabetes educators and CF patients concerning the issues surrounding CFRD, and it will be reviewed and updated in 2016.

Burgess JC, Bridges N, Banya W, Gyi KM, Hodson ME, Bilton D, Simmonds NJ.  HbA1c as a screening tool for cystic fibrosis related diabetes.  J Cyst Fibros. 2015 Apr 10. pii: S1569-1993(15)00068-5. doi: 10.1016/j.jcf.2015.03.013. [Epub ahead of print] [ 2 [PubMed]
Early diagnosis of cystic fibrosis (CF) related diabetes (CFRD) is important to improve outcomes. International guidelines recommend an oral glucose tolerance test (OGTT) for all CF patients aged ≥10years – this approach is controversial. The aim of this study was to develop an effective screening tool and reduce the need for a universal OGTT.

Adult CF patients (without CFRD) attending an annual review assessment were recruited prospectively (March 2009-July 2012) into two sequential studies – a primary investigative study followed by validation study. All patients underwent an OGTT and were simultaneously screened by predetermined biochemical/clinical criteria to identify their risk of CFRD. A sensitivity/specificity analysis was performed using the World Health Organisation diabetes criteria as gold standard; modifications were made to improve the screening tool’s accuracy and determine the optimal screening thresholds. This was tested in the validation study.
429 patients (primary, n=94; validation, n=335: mean age=31.7±10.4(SD), 43% female, 77% on pancreatic supplements). Primary study: in predicting a positive OGTT, the test sensitivity was 66.7% and specificity 60%. HbA1c was carried over to the validation study as it was the most discriminative (optimal threshold ≥5.8% (40mmol/mol); receiver operating curve, ROC, score 0.60). Validation study: the number of patients with a normal, impaired and diabetic OGTT was 268(80%), 51(15.2%) and 16(4.8%), respectively. HbA1c provided a test sensitivity, specificity and ROC score of 93.8%, 53.0% and 0.73, respectively.
CONCLUSIONS:
The use of HbA1c≥5.8%(40mmol/mol) is an effective tool for CFRD screening and reduced the need for an OGTT by 50.7%.

Comment:  Marie-Angela Schnyder, Christian Benden, Christoph Schmid  HbA1c: An effective screening tool for cystic fibrosis related diabetes?  DOI: http://dx.doi.org/10.1016/j.jcf.2015.10.010
Caution “Overall, we concur that clinical criteria remain important in diagnostic strategies and treatment decisions, and that in CF patients in good clinical condition, low HbA1c could possibly serve as a tool to reduce the number of oGTTs; however, we strongly recommend oGTTs in patients with advanced CF lung disease and poor clinical condition with a high pretest probability of insulinopenia; since these patients may well benefit from insulin treatment, beyond the control of hyperglycaemia, ideally improving muscle and lung functions”

Comment:  John Widger, Shihab Hameed, Chee Y. Ooi, Charles VergeUsing HbA1c as a screening tool for Cystic Fibrosis Related Diabetes  DOI: http://dx.doi.org/10.1016/j.jcf.2015.10.009
Support “The HbA1c is a relatively cheap and simple one off blood test that would seem to fit the brief perfectly”.

2015  Uc A; Olivier AK; Griffin MA; Meyerholz DK; Yao J; Abu-El-Haija M; Buchanan KM; Vanegas Calderon OG; Abu-El-Haija M; Pezzulo AA; Reznikov LR; Hoegger MJ; Rector MV; Ostedgaard LS; Taft PJ; Gansemer ND; Ludwig PS; Hornick EE; Stoltz DA; Ode KL; Welsh MJ; Engelhardt JF; Norris AW. Glycaemic regulation and insulin secretion are abnormal in cystic fibrosis pigs despite sparing of islet cell mass.  Clin Sci 2015;  128(2):131-42.  [PubMed]
Because exocrine pancreatic disease is similar between humans and pigs with CF, the CF pig model has the potential to contribute significantly to the understanding of CFRD pathogenesis. The authors determined the structure of the endocrine pancreas in fetal, newborn and older CF and non-CF pigs and assessed endocrine pancreas function by intravenous glucose tolerance test (IV-GTT).
In fetal pigs, pancreatic insulin and glucagon density was similar between CF and non-CF. In newborn and older pigs, the insulin and glucagon density was unchanged between CF and non-CF per total pancreatic area, but increased per remnant lobular tissue in CF reflecting exocrine pancreatic loss. Although fasting glucose levels were not different between CF and non-CF newborns, CF newborns demonstrated impaired glucose tolerance and increased glucose area under the curve during IV-GTT. Second phase insulin secretion responsiveness was impaired in CF newborn pigs and significantly lower than that observed in non-CF newborns. Older CF pigs had elevated random blood glucose levels compared with non-CF.
In summary, glycaemic abnormalities and insulin secretion defects were present in newborn CF pigs and spontaneous hyperglycaemia developed over time. Functional changes in CF pig pancreas were not associated with a decline in islet cell mass.

The authors conclude their results suggest that functional islet abnormalities, independent of structural islet loss, contribute to the early pathogenesis of CFRD.

2015 Roberts R; Speight L; Lee J; George L; Ketchell RI; Lau D; Duckers J.  Retinal screening of patients with cystic fibrosis-related diabetes in Wales – a real eye opener.  J Cyst Fibros 2015; 14(2):282-4. [PubMed]
In the UK the National Screening Committee recommends annual retinal screening for all diabetic patients over the age of twelve years. Currently, patients on insulin therapy for Cystic Fibrosis-Related Diabetes Mellitus (CFRD) at the All Wales Adult Cystic Fibrosis Service, UK are invited for annual screening.  67 of the 228 (29%) patients attending the CF centre were receiving insulin therapy. Of the 43 who had retinal scans, 18 (42%) had evidence of retinopathy. Patients with retinopathy had a higher mean HbA1c (p=0.04), mean duration of diabetes and mean duration on insulin (p<0.001).
Almost half of the patients screened had evidence of retinopathy but over a third of the patients with CFRD did not attend screening appointments. Improving patient uptake of retinal scans will become increasingly important in an ageing CF population.

– A disappointing proportion of eligible patients attended for retinal screening particularly in view of the high percentage of retinopathy in those who did attend.

2015 Knudsen KB, Mathiesen ER, Eriksen V, Skov M, Nielsen KG, Johannesen J, Pressler T.  The development of diabetes among Danish cystic fibrosis patients over the last two decades. Pediatr Diabetes. 2015 May;16(3):219-26. doi: 10.1111/pedi.12143. Epub 2014 Jun 1. [PubMed] 
Cystic fibrosis (CF)-related diabetes (CFRD) is correlated with age and has been associated with a decline in body mass index (BMI), pulmonary function, and survival. Over the last two decades, the focus has been on the early diagnosis and treatment of diabetes; therefore, in this study, we evaluated the status of the current clinical condition and survival in our CF population. In addition, we also aimed to investigate the incidence of diabetes among adolescence over time and to identify characteristics associated with early diabetes onset.
A retrospective chart review of a birth cohort consisting of 161 CF patients born between 1975 and 1994 and followed until 2011.
Over two decades, the incidence of CFRD among 11- to 16-year-old children remained unchanged at 12-14%, while the proportion of children with chronic pulmonary infection at age 10 declined from 31 to 8% (p < 0.001). Severe CF-mutation, i.e., group I and II mutations, were associated with diabetes (p = 0.003). Female gender was borderline associated with diabetes among adolescents (p = 0.06). No significant worsening in pulmonary function, BMI or survival was identified when comparing CFRD patients to CF patients without CFRD.
The incidence of diabetes among adolescence with CF in the Copenhagen clinic has not changed over the last two decades. Severe CF mutations are a risk factor for CFRD, and female gender is borderline associated with CFRD among adolescents. Pulmonary function, BMI and survival were comparable regardless of the onset

Burgess JC, Bridges N, Banya W, Gyi KM, Hodson ME, Bilton D, Simmonds NJ. HbA1c as a screening tool for cystic fibrosis related diabetes.   J Cyst Fibros. 2016 Mar;15(2):251-7. doi: 10.1016/j.jcf.2015.03.013. Epub 2015 Apr 11.[PubMed]
                             Early diagnosis of cystic fibrosis (CF) related diabetes (CFRD) is important to improve outcomes. International guidelines recommend an oral glucose tolerance test (OGTT) for all CF patients aged ≥10 years – this approach is controversial. The aim of this study was to develop an effective screening tool and reduce the need for a universal OGTT.Adult CF patients (without CFRD) attending an annual review assessment at the Royal Brompton, London were recruited prospectively (March 2009-July 2012) into two sequential studies – a primary investigative study followed by validation study. All patients underwent an OGTT and were simultaneously screened by predetermined biochemical/clinical criteria to identify their risk of CFRD. A sensitivity/specificity analysis was performed using the World Health Organisation diabetes criteria as gold standard; modifications were made to improve the screening tool’s accuracy and determine the optimal screening thresholds. This was tested in the validation study.429 patients (primary, n=94; validation, n=335: mean age=31.7 ± 10.4(SD), 43% female, 77% on pancreatic supplements). Primary study: in predicting a positive OGTT, the test sensitivity was 66.7% and specificity 60%. HbA1c was carried over to the validation study as it was the most discriminative (optimal threshold ≥5.8% (40 mmol/mol); receiver operating curve, ROC, score 0.60). Validation study: the number of patients with a normal, impaired and diabetic OGTT was 268 (80%), 51(15.2%) and 16(4.8%), respectively. HbA1c provided a test sensitivity, specificity and ROC score of 93.8%, 53.0% and 0.73, respectively.

The authors concluded that the use of HbA1c ≥ 5.8%(40 mmol/mol) is an effective tool for CFRD screening and reduced the need for an OGTT by 50.7%.

2016 Boudreau V, Coriati A, Desjardins K, Rabasa-Lhoret R. Glycated hemoglobin cannot yet be proposed as a screening tool for cystic fibrosis related diabetes.  J Cyst Fibros. 2016 Mar;15(2):258-60. doi: 10.1016/j.jcf.2016.02.005. [PubMed]

With improved life expectancy of cystic fibrosis (CF) patients, CF-related diabetes (CFRD) has become a major complication. The oral glucose tolerance test (OGTT) is the standard test to detect it. However, the use of OGTT is controversial, in addition to being a burden for patients and the treatment team. Research to find alternative ways of testing is ongoing. While some propose that glycated hemoglobin (HbA1c) may be an effective alternative, our past results suggest otherwise.A new analysis involving the OGTT and HbA1c values of 207 patients, between 2004 and 2015, proposes that the threshold of a lower value of HbA1c of ≥5.8%(39.9 mmol/mol) gives a sensitivity of 68.2% and a specificity of 60.5%. With such sensitivity to identify patients in need of an OGTT, 31.8% of CFRD diagnosis would be missed if the suggested HbA1c value of ≥5.8% was used as a screening tool to identify patients in need of OGTTs.

– Considering their results, the authors believe the HbA1c does not possess the characteristics of a suitable screening test for CFRD as 31.8% would be missed.

Dr. Remi Rabasa-Lhoret (figure), the corresponding author, is Director of the Metabolic Unit in the Nutrition Department in the endocrine service of the Montreal University Hospital.

2016  Widger J; Hameed S; Ooi CY; Verge C.  Using HbA1c as a screening tool for Cystic Fibrosis Related Diabetes.  J Cyst Fibros 2006; 15(2):263-4. [PubMed]

Using the proposed cut off for HdA1c (5.8%) would fail to detect patients with early glucoseabnormalities. Therefore until it is clarified if insulin treatment should be offered to patients with early insulin deficiency the authors caution against the use od HbA1c as a screening tool in this population.

John Widger (figure 8) is Staff Specialist and Head of Respiratory Medicine, Sydney Children’s Hospital, Randwick

2016 Schnyder MA; Benden C; Schmid C.  bA1c: An effective screening tool for cystic fibrosis related diabetes?.  J Cyst Fibros 2016; 15(2):261-2.[PubMed]

Recently HbA1c has been accepted as a diagnostic criterion fir Type 1 and type 2 diabetes if 6.5% or more. This would have a poor sensitivity to detect CFRD – the same is true for fasting plasma glucose of 7mmol/l or more. By contrast a 2hr glucose value of 11.1mmol/l or more remains an accepted criterion for Type1 and type2 diabetes and CFRD. In the context of severely ill patients referred to this transplant centre, impaired insulin secretion is also important and is more reliably reflected and identified by a high 2hr plasma glucose than by a high FPG or HbA1c. In patients in good condition, a low HbA1c could possibly serve as to reduce the numbers of oral glucose tolerance tests (oGTT) but in patients with advanced CF lung disease in poor condition with a high probability of insulinopenia oGTT is preferred as these patients my benefit from insulin treatment beyond the control of hyperglycaemia ideally improving muscle and lung functions.

Marie-Angela Schnyder (figure) is a member of the Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital, Zurich.

Onady GM; Stolfi A.  Insulin and oral agents for managing cystic fibrosis-related diabetes. [Review][Update of Cochrane Database Syst Rev. 2013;(7):CD004730; PMID: 23893261]    Cochrane Database of Systematic Reviews. 4:CD004730, 2016. [PubMed]
The Cystic Fibrosis Foundation recommends both short-term and long-acting insulin therapy when cystic fibrosis-related diabetes has been diagnosed. Diagnosis is based on: an elevated fasting blood glucose level greater than 6.94 mmol/liter (125 mg/deciliter); or oral glucose tolerance tests greater than 11.11 mmol/liter (200 mg/deciliter) at two hours; or symptomatic diabetes for random glucose levels greater than 11.11 mmol/liter (200 mg/deciliter); or glycated hemoglobin levels of at least 6.5.

This is a detailed review and the authors have not found any significant conclusive evidence that long-acting insulins, short-acting insulins or oral hypoglycemic agents have a distinct advantage over one another in controlling hyperglycemia or clinical outcomes associated with cystic fibrosis-related diabetes. While some cystic fibrosis centers use oral medications to help control diabetes, the Cystic Fibrosis Foundation (USA) clinical practice guidelines support the use of insulin therapy and this remains the most widely-used treatment method. Randomized controlled trials specifically related to controlling diabetes with this impact on the course of pulmonary disease process in cystic fibrosis continue to be a high priority.There is no demonstrated advantage yet established for using oral hypoglycemic agents over insulin, and further trials need to be evaluated to establish whether there is clear benefit for using hypoglycemic agents. Agents that potentiate insulin action, especially agents with additional anti-inflammatory potential should be further investigated to see if there may be a clinical advantage to adding these medications to insulin as adjuvant therapy.

2016 Taylor-Cousar JL, Janssen JS, Wilson A, Clair CG, Pickard KM, Jones MC, Brayshaw SJ, Chacon CS, Barboa CM, Sontag MK4, Accurso FJ, Nichols DP, Saavedra MT, Nick JA.  Glucose >200 mg/dL during Continuous Glucose Monitoring Identifies Adult Patients at Risk for Development of Cystic Fibrosis Related Diabetes J Diabetes Res. 2016;2016:1527932. doi: 10.1155/2016/1527932. Epub 2016 Nov 24.[PubMed]

Guidelines suggest that screening for CFRD be performed annually using the 2-hour 75-gram oral glucose tolerance test (OGTT). Adherence to recommended screening has been poor, with only approximately one-quarter of adults with CF undergoing OGTT in 2014. Use of continuous glucose monitoring (CGM) for diagnosis may become an alternative. The authors objective was to determine whether abnormal CGM predicts subsequent development of CFRD, lung function, and body mass index (BMI) decline and increased rate of CF pulmonary exacerbations in adults with CF.

In a prospective single center pilot trial from September 2009 to September 2010, 21 adult patients due for routine OGTT were recruited to complete simultaneous 3-day CGM and 2-hour 75 gram OGTT. Subsequently, clinical information was reviewed from 2008 to 2015.

There was a moderate correlation between interpreted results of 2-hour OGTT and CGM (p = 0.03); CGM indicated a greater level of glucose impairment than OGTT. Glucose >200 mg/dL by CGM predicted development of CFRD (p = 0.0002).

Jennifer L Taylor-Cousar (figure) is a paediatric and adult pulmonologist at National Jewish Health.

2016 Armaghanian N, Brand-Miller JC Markovic TP, Steinbeck KS. Hypoglycaemia in cystic fibrosis in the absence of diabetes: A systematic review.  J Cyst Fibros. 2016 Mar 22. pii: S1569-1993(16)30003-0. doi: 10.1016/j.jcf.2016.02.012. [Epub ahead of print] [PubMed]
A total of 11 studies and five evidence-based guidelines met the inclusion criteria. Prevalence rates of hypoglycaemia unrelated to diabetes varied between studies (7-69%). There was no unifying definition of hypoglycaemia in the absence of diabetes. Only two evidence based guidelines reported possible management strategies.- The systematic review found limited data on this clinical problem and supports the need for high quality methodological studies that are able to describe the experience and the aetiology of hypoglycaemia in CF.

Ballmann M,Hubert D,Assael BM,Staab D,Hebestreit A,Naehrlich L,Nickolay T,Prinz N,Holl RW;CFRD Study Group. Repaglinide versus insulin for newly diagnosed diabetes in patients withcystic fibrosis: a multicentre, open-label, randomised trial. Lancet Diabetes Endocrinol.2018Feb;6(2):114-121. doi: 10.1016/S2213-8587(17)30400-X. Epub 2017 Dec 5.[PubMed]
A study to assess the efficacy and safety of oral anti-diabetic drugs. A multicentre, open-label, comparative, randomised trial in 49 centres in Austria, France, Germany, and Italy. Eligible patients had cystic fibrosis, were older than 10 years, and had newly diagnosed diabetes.

Thirty-four patients were enrolled in the repaglinide group and 41 in the insulin group, of whom 30 and 37, respectively, were included in the analyses. At 24 months, glycaemic control was similar in the repaglinide and insulin groups (mean change in HbA_1cconcentration from baseline 0·2% [SD 0·7%], 1·7 mmol/mol [8·1 mmol/mol] with repaglinide vs -0·2% [1·3%], -2·7 mmol/mol, [14·5 mmol/mol] with insulin; mean difference between groups -0·4%, (95% CI -1·1 to 0·2 [-4·4 mmol/mol, -11·5 to 2·7], p=0·15). The most frequent adverse events were pulmonary events (43 [40%] of 107 in the repaglinide group and 60 [45%] of 133 in the insulin group), and the most frequent serious adverse events were pulmonary events leading to hospital admission (five [50%] of ten and seven [54%] of 13, respectively).

The authors concluded that repaglinide for glycaemic control in patients with cystic-fibrosis-related diabetes is as efficacious and safe as insulin

Lam GY, Doll-Shankaruk M, Dayton J, Rodriguez-Capote K, Higgins TN, Thomas D, Mulchey K, Smith MP, Brown NE, Leung WM, Estey MP.  The use of fructosamine in cystic fibrosis-related diabetes (CFRD) screening.    J Cyst Fibros. 2018 Jan;17(1):121-124. doi: 10.1016/j.jcf.2017.05.010. Epub 2017 Jun 22[PubMed
To determine whether serum fructosamine correlates with glycaemic control and clinical outcomes in patients being screened for cystic fibrosis-related diabetes (CFRD).   Fructosamine and FEV₁were measured in patients undergoing a 2 hr. oral glucose tolerance test (OGTT) for CFRD screening. Fractional serum fructosamine (FSF) was calculated as fructosamine/total protein.    FSF exhibited a positive correlation with 2hr OGTT results (r²=0.3201, p=0.009), and ROC curve analysis suggested that FSF can identify patients with an abnormal OGTT (AUC=0.840, p=0.0002). FSF also exhibited a negative correlation with FEV₁ (r²=0.3732, p=0.035). Patients with FSF≥3.70μmol/g had significantly lower FEV₁ (median 47%) compared to those with FSF<3.70μmol/g (median 90%; p=0.015).

The authors concluded that fractional serum fructosamine correlated with both OGTT results and FEV₁, and reliably identified patients with abnormal OGTT results. They consider this simple blood test shows potential as an effective tool in CFRD screening.

Bridges N, Rowe R, Holt RIG.Unique challenges of cystic fibrosis-related diabetes.   Diabet Med. 2018 Apr 23. doi: 10.1111/dme.13652. [Epub ahead of print]    [PubMed]

Individuals with cystic fibrosis and pancreatic insufficiency have a gradual decline in insulin secretion over time, which results in an increase in the prevalence of diabetes with age; up to 50% of adults with cystic fibrosis aged over 35-40 years have diabetes. Cystic fibrosis-related diabetes differs from Type 1 and Type 2 diabetes in several ways; there is a pattern of insulin deficiency with reduced and delayed insulin response to carbohydrates but a sparing of basal insulin that results in glucose abnormalities, which are frequently characterized by normal fasting glucose and postprandial hyperglycaemia. Insulin deficiency and hyperglycaemia, even at levels which do not reach the threshold for a diagnosis of diabetes, have an adverse impact on lung function and clinical status in people with cystic fibrosis. Although the risk of microvascular complications occurs as in other forms of diabetes, the main reason for treatment is to prevent deterioration in lung function and weight loss; treatment may therefore be required at an earlier stage than for other types of diabetes. Treatment is      usually with insulin, but management needs to take into account all the other medical issues that arise in cystic fibrosis. This article is protected by copyright. All rights reserved

Professor Richard Holt is Professor in Diabetes and Endocrinology within Medicine at the University of Southampton                                                         Dr. Nicola Bridges is a Paediatric Endocrinologist based at Chelsea and Westminster Hospital, London and also works at the Royal Brompton Hospital and St Mary’s Hospital.
Dr. Rachel Rowe is Consultant Physician, Diabetologist at the University Hospital of South Manchester NHS Foundation Trust.

Norris AW.  Is Cystic Fibrosis Related Diabetes Reversible? New Data on CFTR Potentiation and Insulin Secretion.Am J Respir Crit Care Med. 2018 Sep 7. doi: 10.1164/rccm.201808-1501ED. [Epub ahead of print] [PubMed]

A discussion on the recent publication of Kelly et el 2018 (see below)    “The Kelly et al (7) result provides hope that restoration of CFTR function might treat and prevent CFRD. However, given the current limited understanding of CFRD pathogenesis, there remains considerable uncertainty. It is possible that the fixed defects in the pancreas might prove too great a burden for the endocrine pancreas to maintain sufficient long term function. Since pancreatic disease begins in utero, it could be envisioned that CFTR restoration may need to begin before birth in order to minimize lifetime CFRD risk. Longer term clinical studies, including in patients with CFRD, will help clarify whether such an intensive approach is needed. Likewise, mechanistic study of the early life determinants of CFRD in relevant CF animal models will help unravel the fixed versus reversible underpinnings of diabetes in CF”.

Dr. Andrew Norris is Professor of Biochemistry and Pedaitrics – Endocrinology and Diabetes,University of Iowa, Iowa City, Iowa.

Andrea Kelly ,  Diva D De Leon ,  Saba Sheikh ,  Devaney Camburn ,  Christina Kubrak ,  Amy J Peleckis ,  Darko Stefanovski ,  Denis Hadjiliadis ,  Michael R Rickels , and  Ronald C Rubenstein Islet Hormone and Incretin Secretion in Cystic Fibrosis Following 4-months of Ivacaftor Therapy. Am J Respir Cri Care 2018 Aug 21.    https://doi-org.rsm.idm.oclc.org/10.1164/rccm.201806-1018OC    [PubMed]

Diabetes is associated with worse cystic fibrosis (CF) outcomes. The CFTR potentiator ivacaftor is suggested to improve glucose homeostasis in individuals with CF. Objective: The authors tested the hypothesis that clinically-indicated ivacaftor would be associated with improvements in glucose tolerance and insulin and incretin secretion.                                Methods: Oral glucose tolerance tests, mixed meal tolerance tests, and glucose-potentiated arginine tests were compared pre- and 16-weeks post-ivacaftor initiation in CF participants with at least one CFTR gating or conductance mutation. Meal-related 30- (early-phase) and 180-min incremental area under the curves were calculated as responses for glucose, insulin, C-peptide, and incretin hormones, glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide. First-phase insulin secretion, glucose-potentiation of arginine-induced insulin secretion, and disposition index were characterized by glucose-potentiated arginine tests.                 Results: Twelve subjects (6M/6F; 7 normal/5 abnormal glucose tolerance [AGT], oral glucose tolerance test one-hour glucose>155 and two-hour glucose<200 mg/dL) of median [min-max] age: 13.8y [6.0-42.0], BMI-Z: 0.66 [-2.4-1.9], and FEV1%-predicted: 102 [39-122] completed the study. Glucose tolerance normalized in one AGT subject. Ivacaftor treatment did not alter meal responses except for an increase in early-phase C-peptide (P=0.04). First-phase (P=0.001) and glucose-potentiation of arginine-induced (P=0.027) insulin secretion assessed by acute C-peptide responses improved after ivacaftor treatment. Consistent with an effect on β-cell function, the disposition index relating the amount of insulin secreted for insulin sensitivity also improved (P=0.04).

Conclusions: Insulin secretion improved following four months of clinically-indicated ivacaftor therapy in this relatively young group of CF patients with normal to mildly impaired glucose tolerance, while incretin secretion remained unchanged.

Andrea Kelly works at the Children’s Hospital of Philadelphia, Endocrinology/Diabetes, Philadelphia, Pennsylvania, United States

Li A, Vigers T, Pyle L, Zemanick E, Nadeau K, Sagel SD, Chan CL.Continuous glucose monitoring in youth with cystic fibrosis treated with lumacaftor-ivacaftor.  2018 Aug 10. pii: S1569-1993(18)30718-5. doi: 10.1016/j.jcf.2018.07.010. [Epub ahead of print]    [PubMed]
The effects of lumacaftor-ivacaftor therapy on glycemia have not been thoroughly investigated. Continuous glucose monitoring (CGM) provides detailed information about glycemic patterns and detects glucose abnormalities earlier than traditional screening tools for diabetes.     CGM measures, HbA1c, and oral glucose tolerance test (OGTT) results were collected and within-subject results compared in F508del homozygous youth with CF before and after initiation of lumacaftor-ivacaftor using the Wilcoxon signed-rank test.

Nine youth with CF (6 males, median age 12.7 years) were enrolled. CGM was performed in all participants before (median 26 weeks) and after lumacaftor-ivacaftor (median 29 weeks). HbA1c and fasting plasma glucose increased (p = .02) after lumacaftor-ivacaftor initiation. No changes in OGTT 1 h or 2 h glucose nor CGM measures were observed overall. When analyzed by sex, males showed lower glycemic variability, as reflected by the mean amplitude of glycemic excursions, on the post-treatment CGM.

Glycemic abnormalities persisted in CF patients treated with lumacaftor-ivacaftor, although sex-dependent differences in glycemic response to treatment may exist.

Frost F, Dyce P, Nazareth D, Malone V, Walshaw MJ.    Continuous glucose monitoring guided insulin therapy is associated with improved clinical outcomes in cystic fibrosis-related diabetes.    J Cyst Fibros. 2018 Jun 6. pii: S1569-1993(18)30587-3. doi: 10.1016/j.jcf.2018.05.005. [Epub ahead of print]   [PubMed]
Continuous glucose monitoring (CGM) allows assessment of day to day glycaemic excursions and detects early glucose handling abnormalities that may not be apparent on oral glucose tolerance testing (OGTT). However, there is little published evidence as to whether these early dysglycaemic changes are amenable to treatment. We present outcomes following CGM guided insulin initiation at our centre.   Adults without a prior diagnosis of cystic fibrosis related diabetes (CFRD) whom underwent >72 h CGM at our adult CF centre were included in the study. Clinical outcomes including weight and pulmonary function changes over the next 12 months were compared between groups based on CGM results and subsequent management.

CGM profiles for 59 patients were analysed. Insulin was commenced in 37 patients who had evidence of hyperglycaemia on CGM. Significant improvements in mean [95% confidence intervals] forced expiratory volume in 1 s (FEV₁) (+4.3% predicted [1.06-7.48], p = 0.01) and weight (+1.2 kg [0.32-2.15], p = 0.01) were observed at 3 months in the insulin group. Annual rate of pulmonary function decline was also improved following insulin initiation.   Insulin treatment targeted towards glycaemic excursions seen on CGM is associated with improvements in lung function and weight with subsequent reduced pulmonary function decline.

Kessler L.Treatment of cystic fibrosis-related diabetes.   Lancet Diabetes Endocrinol. 2018 Mar;6(3):167. doi: 10.1016/S2213-8587(18)30042-1. No abstract available.[PubMed]
Laurence Kessler commenting on the recent Ballman et al study (Lancet Diabetes Endocrinol 2018; 6:114-121) comparing the oral anti-diabetic drug repaglinide and insulin for CF related diabetes both of which they found resulted in a similar degree of control. She also mentions a similar previous study by Antoinette Moran et al (Diabetes Care 2009; 32:1783-1788) where those given insulin had an increase in BMI. Kessler notes that the kinetics of regular insulin, with a peak after 3 hours and 6 hour action, does not allow optimum postprandial hyperglycaemia control. He suggest that insulin in the Ballman study may have been under dosed to avoid delayed hypoglycaemia – accounting for the absence of weight gain in their insulin group. She mentions the advantage of the newer fast acting insulins (Fiasp, Novo Nordisk) and suggests the availability of the new ultra-fast insulins should enable the design of suitable trials to investigate the effect of treating insulin deficiency in CF related diabetes on metabolism, nutritional and pulmonary outcomes.

Laurence Kessler is Professor in Endocrinology and Metabolic Disorders, Faculty of Medicine, Strasbourg.

Ballman M, Holl RW.Treatment of cystic fibrosis-related diabetes – Authors’ reply. Lancet Diabetes Endocrinol. 2018 Mar; 6(3):167-168. doi: 10.1016/S2213-8587(18)30043-3. No abstract available.     [PubMed]
In response to Lawrence Kessler (Lancet Diabetes Endocrinol. 2018 Mar;6(3):167), Manfred Ballman agrees the control of past-prandial hyperglycaemia can be very difficult in CFRD however do not agree their patients were under dosed to avoid hypoglycaemia.  He also notes that control was good as judged by the mean HbA1c below 7%. They agree that the newer faster insulins may provide better results but observed that more complicated insulin regimes may further add to problems of long term compliance. Finally they note, as a reflection of the problems, although Moran et al. in 2009 called for more trials, the Ballman et trial 2018 was the first to be reported since 2009.

Mannik LA, Chang KA, Annoh PQK, Sykes J, Gilmour J, Robert R, Stephenson AL.  Prevalence of hypoglycemia during oral glucose tolerance testing in adults with cystic fibrosis and risk of developing cystic fibrosis-related diabetes. J Cyst Fibros. 2018 Apr 18. pii: S1569-1993(18)30081-X. doi: 10.1016/j.jcf.2018.03.009. [Epub ahead of print] [Pubmed]
Few studies have examined whether hypoglycemia during the OGTT increases the risk of developing CF-related diabetes (CFRD). Objectives of this study were to describe the characteristics of CF patients with hypoglycemia during the OGTT and to determine the incidence and time to development of CFRD in those with hypoglycaemia.   138 patients (29.6%) experienced hypoglycaemia during the OGTT. More males experienced hypoglycaemia compared to no hypoglycemia (69.6% vs. 54.6% respectively; p = 0.003). Those who were heterozygous deltaF508 were more likely to experience hypoglycemia (p = 0.006). Subjects who experienced hypoglycemia were less likely to develop CFRD at ten years compared to no hypoglycemia (12.0% vs. 42.1%, respectively; p < 0.001).

Hypoglycemia following OGTT is common in CF however the 10 year risk of developing CFRD in these patients was low. Males and those who were heterozygous deltaF508 were at higher risk for hypoglycemia.

Adler A .  To treat or not to treat: dysglycaemia in cystic fibrosis.  Diabet Med. 2019 Aug 20. doi: 10.1111/dme.14112. [Epub ahead of print] Pubmed]

Good evidence for treating hyperglycaemia in cystic fibrosis is lacking. The accompanying commentary [1] questions whether treating cystic fibrosis-related diabetes (CFRD) and, specifically, lesser degrees of dysglycaemia in people with cystic fibrosis leads to better outcomes [1]. Although epidemiological studies have documented that people with cystic fibrosis and diabetes die earlier than people with cystic fibrosis without diabetes [2], and among people with CFRD, those with higher compared to lower measures of glycaemia also die earlier [3], this evidence falls short of proving that treating people for hyperglycaemia will make them live longer. Warren, then, is correct to offer a ‘reality check’, and chooses to focus not on CFRD, but rather on dysglycaemia, that is, values of blood glucose approaching, but not attaining, the diagnostic criteria for diabetes.

Dr Amanda Adler is consultant physician at Addenbrooke’s Hospital Cambridge with an interest in diabetes. She also has many advisory and administrative roles with in the UK health system.

Li A, Vigers T, Pyle L, Zemanick E, Nadeau K, Sagel SD, Chan CL. Continuous glucose monitoring in youth with cystic fibrosis treated with lumacaftor-ivacaftor. J Cyst Fibros. 2019 Jan;18(1):144-149. doi: 10.1016/j.jcf.2018.07.010. Epub 2018 Aug 10.  [Pubmed]

Nine youths with CF (6 males, median age 12.7 years) were enrolled. CGM was performed in all participants before (median 26 weeks) and after lumacaftor-ivacaftor (median 29 weeks). HbA1c and fasting plasma glucose increased (p = .02) after lumacaftor-ivacaftor initiation. No changes in OGTT 1 h or 2 h glucose nor CGM measures were observed overall. When analyzed by sex, males showed lower glycemic variability, as reflected by the mean amplitude of glycemic excursions, on the post-treatment CGM.

The authors concluded glycemic abnormalities persisted in CF patients treated with lumacaftor-ivacaftor, although sex-dependent differences in glycemic response to treatment may exist.

Dr A Li of  University of Colorado School of Medicine, University of Colorado Anschutz medical Campus Aurora

Dr Christine Chan is a paediatric endocrinologist in Aurora Colorado

orris AW. Is Cystic Fibrosis-related Diabetes Reversible? New Data on CFTR Potentiation and Insulin Secretion.Am J Respir Crit Care Med. 2019 Feb 1;199(3):261-263. doi: 10.1164/rccm.201808-1501ED.  [Pubmed]
Andrew Norris discusses the question as to whether the new molecular therapies will treat or even prevent cystic fibrosis related diabetes. In a clear detailed review of the effect of the new therapies on the treatment and even prevention CFRD. He discusses the study of Kelly et al (abstracted below) and concludes that Kelly and colleagues’s results provide hope that restoration of CFTR function might treat or even prevent CFRD, although there remains considerable uncertainty. He mentions the severity of pancreatic involvement and even the fact that pancreatic damage occurs in utero.

Kelly A, De Leon DD, Sheikh S, Camburn D, Kubrak C, Peleckis AJ, Stefanovski D, Hadjiliadis D, Rickels MR, Rubenstein RC. Islet Hormone and Incretin Secretion in Cystic Fibrosis after Four Months of Ivacaftor Therapy.
Am J Respir Crit Care Med. 2019 Feb 1;199(3):342-351. doi: 10.1164/rccm.201806-1018OC.   [Pubmed]

Oral glucose tolerance tests, mixed-meal tolerance tests, and glucose-potentiated arginine tests were compared pre-ivacaftor initiation and 16 weeks post-ivacaftor initiation in CF participants with at least one CFTR gating or conductance mutation.         Meal-related 30-minute (early phase) and 180-minute incremental area under the curves were calculated as responses for glucose, insulin, C-peptide, and incretin hormones; glucagon-like peptide-1; and glucose-dependent insulinotropic polypeptide. First-phase insulin secretion, glucose potentiation of arginine-induced insulin secretion, and disposition index were characterized by glucose-potentiated arginine stimulation tests.

Twelve subjects completed the study: six male/six female; seven normal/five abnormal glucose tolerance (oral glucose tolerance test 1-h glucose ≥155 and 2-h glucose <200 mg/dl); of median (minimum-maximum) age (13.8 yr [6.0-42.0]), body mass index-Z of 0.66 (-2.4 to 1.9), and FEV1% predicted of 102 (39-122). Glucose tolerance normalized in one abnormal glucose tolerance subject. Ivacaftor treatment did not alter meal responses except for an increase in early phase C-peptide (P = 0.04). First-phase (P = 0.001) and glucose potentiation of arginine-induced (P = 0.027) insulin secretion assessed by acute C-peptide responses improved after ivacaftor treatment. Consistent with an effect on β-cell function, the disposition index relating the amount of insulin secreted for insulin sensitivity also improved (P = 0.04).

The authors concluded insulin secretion improved following 4 months of clinically indicated ivacaftor therapy in this relatively young group of patients with CF with normal to mildly impaired glucose tolerance, whereas incretin secretion remained unchanged.

Dr Andrea Kellyis attending physician in the Division of Endocrinology and Diabetes and Division of Pulmonary Medicine and Cystic Fibrosis Center, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania.

Prentice BJ, Ooi CY, Strachan RE, Hameed S, Ebrahimkhani S, Waters SA, Verge CF, Widger J. Early glucose abnormalities are associated with pulmonary inflammation in young children with cystic fibrosis.  J Cyst Fibros. 2019 Apr 26. pii: S1569-1993(18)30897-X. doi: 10.1016/j.jcf.2019.03.010. [Epub ahead of print]  [Pubmed]

Children with CF are insulin deficient from infancy but very little is known about the impact of glucose abnormalities in early life. We aimed to identify and describe interstitial glucose levels in CF children <6 years and to evaluate the association with pulmonary infection and inflammation.  The authors assessed 18 children (5 females) with median age of 3.2 years (range 0∙9-5.5) with Continuous Glucose Monitoring for 3 days. Bronchoalveolar lavage (BAL) fluid was cultured for known pathogenic microbial agents and assessed for total white blood cells, percentage of neutrophils and IL-8 level. Peak sensor glucose (SG) was >11.1 mmol/L in 39% of participants. The percentage neutrophil count on BAL was positively correlated with elevated SG (peak SG rs = 0.48, p = .044) and with glucose variability (SG standard deviation r = 0.62, β = 38.5, p = .006). BAL IL-8 level was significantly correlated with all measures of CGM hyperglycemia including % time > 7.8 mmol/L (p = .008) and standard deviation (p < .001). Participants with a history of Pseudomonas aeruginosa had a higher % time > 7.8 mmol/L glucose (16% versus 3%, p = .015)308694930869491

The authors concluded children with CF frequently demonstrate elevated SG levels before age 6 years, which are associated with increased pulmonary inflammation and Pseudomonas aeruginosa infection. Transient SG elevations into the diabetic range (≥11.1 mmol/L) were identified in children from 1 year of age.

Dr Bernadette Prentice is a Respiratory Paediatrician in the Department of Respiratory Medicine, Sydney Children’s Hospital, Randwick, NSW, Australia.

Choudhury M, Taylor P, Morgan PH, Duckers J, Lau D, George L, Ketchell RI, Wong FS.Association between HbA1c and the development of cystic fibrosis-related diabetes.   Diabet Med. 2019 Jan 30. doi: 10.1111/dme.13912. [Epub ahead of print]  [Pubmed]
A study to examine HbA1c as a predictor of risk for future development of cystic fibrosis-related diabetes and to assess the association with the development of retinopathy in people with cystic fibrosis-related diabetes.   The authors considered there is a link between HbA1c level and the future development of dysglycaemia in cystic fibrosis based on oral glucose tolerance test, as well as microvascular outcomes. Although current guidance does not advocate the use of HbA1c as a diagnostic tool in cystic fibrosis-related diabetes, it may be of clinical use in determining individuals at risk of future development of cystic fibrosis-related diabetes.

From the All Wales Adult Cystic Fibrosis Centre, University Hospital Llandough, Cardiff, UK. and the Diabetes Research Group, Division of Infection and Immunity, Cardiff, UK.
Dr Ian Ketchell is Director of the Adult CF Centre
Dr Jamie Duckers is consultant in CF and lead for the CF Research Programme
Dr Dawn Lau is consultant in CF and with a special interest in Education
Professor Susan Wong, School of Medicine, Cardiff has conducted extensive research into type 1 diabetes and immunotherapy to prevent diabetes

Li A, Vigers T, Pyle L, Zemanick E, Nadeau K, Sagel SD, Chan CL. Continuous glucose monitoring in youth with cystic fibrosis treated with lumacaftor-ivacaftor. J Cyst Fibros.2019 Jan;18(1):144-149. doi: 10.1016/j.jcf.2018.07.010. Epub 2018 Aug 10. [Pubmed]

Prentice BJ, Ooi CY, Strachan RE, Hameed S, Ebrahimkhani S, Waters SA, Verge CF, Widger J. Early glucose abnormalities are associated with pulmonary inflammation in young children with cystic fibrosis. J Cyst Fibros. 2019 Apr 26. pii: S1569-1993(18)30897-X. doi: 10.1016/j.jcf.2019.03.010. [Epub ahead of print] [Pubmed]

Children with CF are insulin deficient from infancy but very little is known about the impact of glucose abnormalities in early life. We aimed to identify and describe interstitial glucose levels in CF children <6 years and to evaluate the association with pulmonary infection and inflammation. The authors assessed 18 children (5 females) with median age of 3.2 years (range 0∙9-5.5) with Continuous Glucose Monitoring for 3 days. Bronchoalveolar lavage (BAL) fluid was cultured for known pathogenic microbial agents and assessed for total white blood cells, percentage of neutrophils and IL-8 level. Peak sensor glucose (SG) was >11.1 mmol/L in 39% of participants. The percentage neutrophil count on BAL was positively correlated with elevated SG (peak SG rs = 0.48, p = .044) and with glucose variability (SG standard deviation r = 0.62, β = 38.5, p = .006). BAL IL-8 level was significantly correlated with all measures of CGM hyperglycemia including % time > 7.8 mmol/L (p = .008) and standard deviation (p < .001). Participants with a history of Pseudomonas aeruginosa had a higher % time > 7.8 mmol/L glucose (16% versus 3%, p = .015).

The authors concluded children with CF frequently demonstrate elevated SG levels before age 6 years, which are associated with increased pulmonary inflammation and Pseudomonas aeruginosa infection. Transient SG elevations into the diabetic range (≥11.1 mmol/L) were identified in children from 1 year of age.

Dr Bernadette Prentice is a Respiratory Paediatrician in the Department of Respiratory Medicine, Sydney Children’s Hospital, Randwick, NSW, Australia.

Sergeev V, Chou FY, Lam GY, Hamilton CM, Wilcox PG, Quon BS. The Extra-pulmonary Effects of CFTR Modulators in Cystic Fibrosis.  Ann Am Thorac Soc. 2019 Oct 29. doi: 10.1513/AnnalsATS.201909-671CME. [Epub ahead of print] Full article can be downloaded from (https://www.researchgate.net/profile/Valetnine_Sergeev) .[Pubmed]

The effects of CFTR modulators on lung function, pulmonary exacerbations, and quality of life have been well documented.

However, CF is a multi-organ disease and therefore an evidence base is emerging on the systemic effects of CFTR modulators beyond the pulmonary system. This is of great clinical importance as many of these studies provide proof-of-concept that CFTR modulators might be used one day to prevent or treat extra-pulmonary manifestations stemming from CFTR dysfunction. In this concise review of the literature, the authors summarize the results of key publications that have evaluated the effects of CFTR modulators on weight and growth, pancreatic function, the gastrointestinal and hepatobiliary systems, sinus disease, bone disease, exercise tolerance, fertility, mental health, and immunity. While many of these studies have reported beneficial extra-pulmonary effects related to the use of ivacaftor (IVA) in CF patients with at least one gating mutation, most of the evidence is low or very low quality given the limited number of patients evaluated and the lack of a control group. Based on an even smaller number of studies evaluating the extra-pulmonary effects of lumacaftor-ivacaftor (LUM-IVA), the benefits are less clear. While limited, these studies may provide the basis for future clinical trials to evaluate CFTR modulators on the extra-pulmonary manifestations of CF

Dr Valentine Sergeev is in the Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada

Dr Bradley S Quon, the corresponding author, is at the Centre for Heart Lung Innovation, Vancouver.

Ogbolu C, Arregui-Fresneda I, Daniels T, Holt RIG. Some young adults with cystic fibrosis-related diabetes may safely stop insulin without any adverse clinical sequelae.  Diabet Med. 2020 Mar 1. doi: 10.1111/dme.14288. [Epub ahead of print]  [Pubmed]

University Hospital Southampton NHS Foundation Trust hosts the Wessex regional CFRD service. In 2018, there were 45 men and 31 women aged 18–25 years attending the service. Of these, 34 had CRFD, 12 had impaired glucose tolerance and 30 had normal glucose tolerance. Of the 34 with CFRD, 29 were treated with insulin at transition from the paediatric to adult services. The organization of care across our region means that children are seen by paediatric teams at different hospitals prior to transition to adult services in Southampton. We were therefore unable to determine why insulin was initiated as we did not have access to the paediatric records. The remaining five people with CFRD were managing their diabetes with lifestyle modification alone.

Fourteen (53%) of the 26 people treated with insulin at the point of transition stopped taking insulin at a mean ± SD age of 20.6 ± 2.4 years. The mean dose of insulin and the mean HbA1c at insulin cessation were 5.8 ± 1.3 units/day and 38 ± 6 mmol/mol (5.7 ± 0.7%), respectively. There were 1-year post-insulin cessation assessments available for all 14 people; 12 were followed for 2 years and eight had 3-year post-insulin cessation data. There were no differences in sex, gene mutation, baseline BMI or lung function between those who stopped insulin compared with those who continued, but those who stopped insulin were older when CFRD was diagnosed (Table 1). After the insulin was stopped, there was no deterioration in HbA1c (P=0.923) or decrease in body weight (P=0.588; Figs 1a,b). No one needed to re-start insulin. Figure 1c shows a small expected decline in lung function with time, but the rate of decline was unaffected by the decision to stop insulin (P=0.135).

In conclusion, although further work is needed to ascertain who can stop insulin safely in early adulthood, the authors suggest that stopping insulin in selected people with CFRD may be one way to simplify their treatment burden.

From the Human Development and Health Academic Unit, Faculty of Medicine, University of Southampton, and the Wessex Adult Cystic Fibrosis Service, Southampton, UK.

Richard Holt is Professor in Diabetes and Endocrinology within Medicine at the University of Southampton.

Prentice BJ, Ooi CY, Verge CF, Hameed S, Widger J. Glucose abnormalities detected by continuous glucose monitoring are common in young children with Cystic Fibrosis.  J Cyst Fibros. 2020 Feb 25. pii: S1569-1993(20)30057-6. doi: 10.1016/j.jcf.2020.02.009. [Epub ahead of print] [Pubmed]

It is not yet known whether continuous glucose monitoring (CGM) abnormalities persist in young children with CF. We evaluated longitudinal CGM results for children with CF < 10 years of age. We performed 3-day CGM at baseline, 12 months, and 24 months on 11 CF children (1 female) initially aged mean (SD) 3.8 (2.5) years. CGM analysis included (i) mean sensor glucose (SG), (ii) standard deviation (SD) for SG, (iii) peak SG and (iv)% time spent above a threshold of 7.8 mmol/L. Only three (3/11, 27%) had normal CGM at all time-points. Nearly three quarters of the participants (8/11, 73%) spent more than 4.5 percent time > 7.8 mmol/L at one time-point, five of whom had an elevated percent time on a subsequent test.

Young children with CF have glucose abnormalities detected by CGM that fluctuate over time.

Dr Bernadette Prentice is a respiratory paediatrician in the Department of Respiratory Medicine, Sydney Children’s Hospital, Randwick, NSW, Australia.

The authors concluded the matched CRMS/CFSPID and CF cohorts showed differences in outcomes. By a mean age of 7.6 years, a high proportion of the CRMS/CFSPID cohort converted to CF. Our results highlight that monitoring at CF clinics until at least 6 years is needed as well as further studies.

 Dr Anne Munck is at the Service des maladies digestives et respiratoires de l’enfant, CRCM, Hôpital Robert Debré, Paris, France.

-The final practical message of this useful paper is important – these infants should be followed up by experts in CF for a long time.

Misgault B, Chatron E, Reynaud Q, Touzet S, Abely M, Melly L, Dominique S, Troussier F, Ronsin-Pradel O, Gerardin M, Mankikian J, Cosson L, Chiron R, Bounyar L, Porzio M, Durieu I, Weiss L, Kessler R, Kessler L.   Effect of one-year lumacaftor-ivacaftor treatment on glucose tolerance abnormalities in cystic fibrosis patients.  J Cyst Fibros. 2020 Mar 19. pii: S1569-1993(20)30073-4. doi: 10.1016/j.jcf.2020.03.002. [Epub ahead of print] [Pubmed
To investigate the effects of 1-year lumacaftor-ivacaftor treatment on abnormalities in glucose tolerance (AGT) in Phe508del homozygous cystic fibrosis (CF) patients.   Untreated CF patients with glucose intolerance or newly diagnosed diabetes were included in a prospective, observational study. After 1-year lumacaftor-ivacaftor treatment, AGT were evaluated by using oral glucose tolerance test.

Forty patients participated. 78% of patients had glucose intolerance and 22% diabetes at baseline. After one-year treatment, 50% of patients had normal glucose tolerance, 40% glucose intolerance, and 10% diabetes (p <0.001). The two-hour OGTT glycemia decreased from 171 (153-197) to 139 (117-162) mg/dL (p <0.001). 57.5% (n = 23) of patients improved their glucose tolerance with a significant decrease in both 1-hour (p<0.01) and 2-hour (p<0.001) OGTT glycemia.

The authors concluded improvements in AGT were observed following 1-year lumacaftor-ivacaftor treatment. Larger studies are needed to comprehensively assess CF transmembrane conductance regulator (CFTR) modulators.

Dr B Misgault  is at the Service d’endocrinologie, diabète et nutrition, Hôpitaux Universitaires de Strasbourg, place de l’hôpital, Strasbourg 67091, France

Kevin J Scully, Gregory Sawicki,  Jessica Kremen, Melissa S Putman.   Monogenic Diabetes in a Child with Cystic Fibrosis: A Case Report and Review of the Literature.   J Endocr Soc 2020 Nov 2;5(1):bvaa165.doi: 10.1210/jendso/bvaa165.eCollection 2021 Jan 1. Free PMC article [Pubmed]

Cystic fibrosis-related diabetes (CFRD) is associated with worsening pulmonary function, lower body mass index, increased infection frequency, and earlier mortality. While the incidence of CFRD is rising, its development in patients under the age of 10 years is uncommon. We present a 9-year-old girl with cystic fibrosis (CF) who presented with a 5-year history of nonprogressive hyperglycemia, demonstrated by abnormal oral glucose tolerance tests, glycated hemoglobin A1c (HbA1c) levels consistently >6.5%, and negative pancreatic autoantibodies. Subsequent genetic testing revealed a pathogenic heterozygous recessive mutation in the GCK gene at c.667G>A (p.Gly223Ser), consistent with a diagnosis of GCK-MODY.

Significant dysglycemia in young children with CF should raise suspicion for alternative aetiologies of diabetes and warrants further investigation. The clinical impact of underlying monogenic diabetes in patients with CF is unclear, and close follow-up is warranted. This case also offers unique insight on the impact of hyperglycemia in the absence of insulin deficiency on CF-specific outcomes.

Dr Kevin Scully is Clinical fellow in the Division of Endocrinology and Pedaitrics, Boston Children’s Hospital, Boston, Massachusetts.

Samuel T Olatunbosun. Chronic incretin-based therapy in cystic fibrosis-related diabetes: A tale of 3 patients treated with sitagliptin for over 5 years. J Cyst Fibros. 2021 Mar 2;S1569-1993(21)00040-0.doi: 10.1016/j.jcf.2021.02.005. Online ahead of print. [Pubmed]

Cystic fibrosis-related diabetes (CFRD) affects 40-50% of adult patients with cystic fibrosis. Insulin therapy is recommended but there are therapeutic challenges, particularly risk of hypoglycemia and aversion of some patients to injectables. An oral incretin-based therapy using a DPP-4i (dipeptidyl peptidase-4 inhibitor), may be a reasonable option, especially in the early stage of the disease. The effect of chronic incretin-based therapy on CFRD is unknown. Here is a report of 3 cases of CFRD patients treated with sitagliptin and the response to therapy over a period of 5-10 years. An effective glycemic control was demonstrated in all the patients, at least during the first 5 years of sitagliptin treatment, and the benefit persisted for a decade in two of them. The secondary failure of the DPP-4i occurred in a CFRD patient with a phenotype resembling type 2 diabetes. A DPP-4i may have an important role in the management of CFRD.

Dr Samuel T Olatunbosun. Uniformed Services, University of the Health Sciences & Department of Endocrinology, David Grant Medical Center, California

– Sitagliptin, sold under the brand name Januvia among others, is an anti-diabetic medication used to treat type 2 diabetes. In the United Kingdom it is listed as less preferred than metformin or a sulfonylurea. It is taken by mouth. It is also available in the fixed-dose combination medication sitagliptin/metformin (Janumet, Janumet XR

Bernadette J Prentice , Adam Jaffe, Shihab Hameed, Charles F Verge, Shafagh Waters, John Widger  Cystic fibrosis-related diabetes and lung disease: an update. Eur Respir Rev. 2021 Feb 16;30(159):200293.doi: 10.1183/16000617.0293-2020.Print 2021 Mar 31.    Free article  [Pubmed]

The development of cystic fibrosis-related diabetes (CFRD) often leads to poorer outcomes in patients with cystic fibrosis including increases in pulmonary exacerbations, poorer lung function and early mortality. This review highlights the many factors contributing to the clinical decline seen in patients diagnosed with CFRD, highlighting the important role of nutrition, the direct effect of hyperglycaemia on the lungs, the immunomodulatory effects of high glucose levels and the potential role of genetic modifiers in CFRD

Florence Racine, Azadeh Shohoudi, Valérie Boudreau, Cécile Q T Nguyen, Marie-Hélène Denis, Katherine Desjardins, Quitterie Reynaud, Rémi Rabasa-Lhoret, Geneviève Mailhot^.  Glycated Hemoglobin as a First-line Screening Test for Cystic Fibrosis‒Related Diabetes and Impaired Glucose Tolerance in Children With Cystic Fibrosis: A Validation Study.  Can J Diabetes 2021 Mar 26;S1499-2671(21)00079-4.doi: 10.1016/j.jcjd.2021.03.005.Online ahead of print.[Pubmed]

Objectives: Our aims in this study were to document the screening rate for cystic fibrosis‒related diabetes (CFRD) in children followed at a cystic fibrosis (CF) clinic in Canada and to evaluate the accuracy of various glycated hemoglobin (A1C) cutoffs to screen for CFRD and impaired glucose tolerance (IGT) in a pediatric CF population.
Methods: The CFRD screening rate was calculated over a follow-up period of up to 8 years among children who attended the CF clinic between 1993 and 2018. Test performance of A1C at various thresholds ranging from 5.5% to 6.2% was compared with the oral glucose tolerance test (OGTT) as the reference method. Children with CF aged ≥10 years with an OGTT performed within 120 days of A1C measurement were included in the analysis.
Results: The overall CFRD screening rate was 53.0%. A total of 256 children were included for the A1C performance analysis, of whom 8.6% had an OGTT-confirmed CFRD diagnosis. An A1C threshold of 5.8% demonstrated an optimal balance between sensitivity (90.9%) and specificity (60.7%) for CFRD screening, leading to a potential reduction of 56.3% of the annual required OGTTs. A1C demonstrated poor accuracy for identifying children with IGT.
Conclusions: An A1C threshold ≥5.8% allows for identification of children requiring further CFRD investigations, which may reduce the clinical burden of children with CF without compromising the ability of early CFRD diagnosis.

Dr Florence Racine is at the Montreal Clinical Research Institute, Montréal, Québec, Canada; Research Centre, CHU Sainte-Justine, Montréal, Québec, Canada; Department of Nutrition, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada

Dr Genevieve Mailhot is Associate Professor Department of Nutrition, University of Montreal

Bernadette J Prentice is a Paediatric Respiratory Physician at the Dept of Respiratory Medicine, Sydney Children’s Hospital, and School of Women’s and Children’s Health, University of New South Wales, Sydney, Randwick, Australia.

– A clear detailed fully referenced excellent review of the present situation regarding CF related diabetes by a respiratory paediatrician and her colleagues. The full article is recommended.

Amy Darukhanavala, Filia Van Dessel, Jannifer Ho, Megan Hansen, Ted Kremer, David Alfego   Use of hemoglobin A1c to identify dysglycemia in cystic fibrosis. PLoS One 2021 Apr 21;16(4):e0250036.doi: 10.1371/journal.pone.0250036. eCollection 2021  Free article   [Pubmed]   (Please see PubMed for full abstract details)

Cystic fibrosis (CF) leads to pancreatic endocrine dysfunction with progressive glycemic disturbance. Approximately 30%-50% of people with CF eventually develop CF-related diabetes (CFRD). Pre-CFRD states progress from indeterminant glycemia (INDET) to impaired fasting glucose (IFG) or impaired glucose tolerance (IGT). Screening guidelines recommend inconvenient annual 2-hour oral glucose tolerance tests (OGTTs), beginning at age 10 years. More efficient methods, such as hemoglobin A1C (HbA1c), have been evaluated, but only limited, relatively small studies have evaluated the association between HbA1c and pre-CFRD dysglycemic states.
This study to determine whether HbA1c is an appropriate screening tool for identifying patients with pre-CFRD dysglycemia to minimize the burden of annual OGTTs.
Results: Mean HbA1c was not significantly different between patients with normal glucose tolerance and those in the INDET (p = 0.987), IFG (p = 0.690), and IGT (p = 0.874) groups. Analysis of variance confirmed the lack of association between HbA1c and glycemia, as mean HbA1c was not significantly different amongst the four categories (p = 0.250).
The authors concluded there is increasing awareness of the impact of pre-CFRD states, including reduced pulmonary function and nutritional status. Unfortunately, our results do not support using HbA1c as a screening tool for pre-CFRD dysglycemia, specifically INDET, IFG, and IGT. Further studies are warranted to evaluate more efficient screening methods to reduce the burden of annual OGTTs.

Dr Amy Darukhanavala is a paediatric endocrinologist and Assistant Professor at the Department of Pediatric Endocrinology, University of Massachusetts Medical Center, Worcester, MA, United States of America.

Bernadette J Prentice , Adam Jaffe, Shihab Hameed, Charles F Verge, Shafagh Waters, John Widger  Cystic fibrosis-related diabetes and lung disease: an update. Eur Respir Rev. 2021 Feb 16;30(159):200293.doi: 10.1183/16000617.0293-2020.Print 2021 Mar 31.    Free article  [Pubmed]

The development of cystic fibrosis-related diabetes (CFRD) often leads to poorer outcomes in patients with cystic fibrosis including increases in pulmonary exacerbations, poorer lung function and early mortality. This review highlights the many factors contributing to the clinical decline seen in patients diagnosed with CFRD, highlighting the important role of nutrition, the direct effect of hyperglycaemia on the lungs, the immunomodulatory effects of high glucose levels and the potential role of genetic modifiers in CFRD.

Bernadette J Prentice is a Paediatric Respiratory Physician at the Dept of Respiratory Medicine, Sydney Children’s Hospital, and School of Women’s and Children’s Health, University of New South Wales, Sydney, Randwick, Australia.

– A clear detailed fully referenced excellent review of the present situation regarding CF related diabetes by a respiratory paediatrician and her colleagues. The full article is recommended.

Helen K Chadwick, Janice Abbott, Margaret Anne Hurley, Louise Dye, Clare L Lawton, Michael W Mansfield, Daniel Peckham.  Cystic fibrosis-related diabetes (CFRD) and cognitive function in adults with cystic fibrosis. J Cyst Fibros  2021 Jun 13;S1569-1993(21)00124-7.doi: 10.1016/j.jcf.2021.04.014.Online ahead of print.  [Pubmed]

Background: Being able to function cognitively is imperative for successful achievement in school, working life, and disease self-management. Diabetes is known to cause changes in brain structure and long-term cognitive dysfunction. This work investigated cystic fibrosis-related diabetes (CFRD) as a mechanism for cognitive impairment in people with CF. It was hypothesised that cognition would be poorer in adults with CFRD than in those with CF without diabetes (CFND) or in healthy controls
Methods: Cognitive performance was assessed using the Cambridge Neuropsychological Test Automated Battery which provides a comprehensive cognitive assessment with tests mapping onto specific brain regions. Demographic, clinical and self-reported health data were documented for all participants. CF specific clinical variables were recorded for the two CF groups.
   Results: Ninety-eight people with CF (49CFRD,49CFND) and 49 healthy controls were recruited. People with CF demonstrated deficits in aspects of verbal and spatial memory, processing speed and cognitive flexibility compared with healthy controls, with all areas of the brain implicated. Those with CFRD had additional difficulties with higher-level processes known collectively as ‘executive function’, which demand greater cognitive load and recruit the prefrontal cortex. Compared with healthy controls, those with CFND and CFRD had an estimated 20% and up to 40% reduction in processing speed respectively.
Conclusion: Managing CF requires higher order executive function. Impairments may be sufficient to interfere with self-care and the ability to perform everyday tasks efficiently. At which point in the CF disease trajectory these difficulties begin, and what may attenuate them, has yet to be determined.

Dr Helen Chadwick is in the School of Psychology, University of Leeds, the Leeds Institute of Medical Research at St James’s, University of Leeds, and the Adult Cystic Fibrosis Unit, St James’s University Hospital, Leeds Teaching Hospitals NHS Trust, Leeds UK

Florence Racine, Azadeh Shohoudi, Valérie Boudreau, Cécile Q T Nguyen, Marie-Hélène Denis, Katherine Desjardins, Quitterie Reynaud, Rémi Rabasa-Lhoret, Geneviève Mailhot^.Glycated Hemoglobin as a First-line Screening Test for Cystic Fibrosis‒Related Diabetes and Impaired Glucose Tolerance in Children With Cystic Fibrosis: A Validation Study.  Can J Diabetes 2021 Mar 26;S1499-2671(21)00079-4.doi: 10.1016/j.jcjd.2021.03.005.Online ahead of print.[Pubmed]

Objectives:Our aims in this study were to document the screening rate for cystic fibrosis‒related diabetes (CFRD) in children followed at a cystic fibrosis (CF) clinic in Canada and to evaluate the accuracy of various glycated hemoglobin (A1C) cutoffs to screen for CFRD and impaired glucose tolerance (IGT) in a pediatric CF population.
Methods:The CFRD screening rate was calculated over a follow-up period of up to 8 years among children who attended the CF clinic between 1993 and 2018. Test performance of A1C at various thresholds ranging from 5.5% to 6.2% was compared with the oral glucose tolerance test (OGTT) as the reference method. Children with CF aged ≥10 years with an OGTT performed within 120 days of A1C measurement were included in the analysis.
Results:The overall CFRD screening rate was 53.0%. A total of 256 children were included for the A1C performance analysis, of whom 8.6% had an OGTT-confirmed CFRD diagnosis. An A1C threshold of 5.8% demonstrated an optimal balance between sensitivity (90.9%) and specificity (60.7%) for CFRD screening, leading to a potential reduction of 56.3% of the annual required OGTTs. A1C demonstrated poor accuracy for identifying children with IGT.
Conclusions:An A1C threshold ≥5.8% allows for identification of children requiring further CFRD investigations, which may reduce the clinical burden of children with CF without compromising the ability of early CFRD diagnosis.

Dr Florence Racine is at the Montreal Clinical Research Institute, Montréal, Québec, Canada; Research Centre, CHU Sainte-Justine, Montréal, Québec, Canada; Department of Nutrition, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada

Dr Genevieve Mailhot is Associate Professor Department of Nutrition, University of Montreal

Sana Hasan, Sarah Soltman, Colleen Wood, Scott M Blackman.  The role of genetic modifiers, inflammation and CFTR in the pathogenesis of Cystic fibrosis related diabetes. J Clin Transl Endocrinol 2021 Dec 10;27:100287.doi: 10.1016/j.jcte.2021.100287.eCollection 2022 Mar [Pubmed]Free PMC article
Cystic fibrosis related diabetes (CFRD) generally reflects insufficient and/or delayed production of insulin, developing slowly over years to decades. Multiple mechanisms have been implicated in the pathogenesis of CFRD. CFTR function itself is a strong determinant of CFRD risk. Variants in CFTR that result in residual CFTR function and exocrine pancreatic sufficiency reduce the risk of CFRD by ten to twenty-fold.
Two groups of hypotheses have been proposed for the mechanism of CFTR impairing insulin secretion in CFRD: (1) β-cell dysfunction results from β cell intrinsic CFTR-dependent mechanisms of insulin secretion. (2) β-cell dysfunction results from factors outside the β cell.
Genome-wide association studies have identified multiple susceptibility genes for type 2 diabetes, including TCF7L2, CDKN2A/B, CDKAL1, and IGF2BP2, as containing genetic modifiers of CFRD. These findings support the presence of intrinsic β cell defects playing a role in CFRD pathogenesis. Oxidative stress and inflammation are β cell-extrinsic mechanisms involved with CFRD. CFTR mutations render β cells more susceptible to oxidative stress and also leads to defects in α-cell function, resulting in reduced suppression of glucagon secretion. Furthermore, CFRD is characterized by β cell loss secondary to intra-islet inflammation. Recent studies have demonstrated the presence of multiple inflammatory mediators within the human CF islet.

This review presents a concise overview of the current understanding of genetic modifiers of CFRD, oxidative stress, islet inflammation, and the controversies about the role of CFTR in the islet.

Dr Sana Hasan is an endocrinologist in the Department of Endocrinology and Metabolism, Cleveland Clinic Foundation, Cleveland, OH, USA.

Swapnil Khare, Marisa Desimone, Nader Kasim, Christine L Chan^.  Cystic fibrosis-related diabetes: Prevalence, screening, and diagnosis. J Clin Transl Endocrinol 2021 Dec 7;27:100290.doi: 10.1016/j.jcte.2021.100290.eCollection 2022 Mar Free PMC article [Pubmed]

Cystic fibrosis-related diabetes (CFRD) is the most common comorbidity in patients with cystic fibrosis (CF). Prevalence of CFRD increases with age and is greater with severe mutations. Other risk factors associated with CFRD are female sex, pancreatic insufficiency, liver disease, need for gastrostomy tube feedings, history of bronchopulmonary aspergillosis, and poor pulmonary function. CFRD is related to worse clinical outcomes and increased mortality. Early diagnosis and treatment have been shown to improve clinical outcomes. Screening for CFRD is recommended with an annual oral glucose tolerance test (OGTT) starting at age 10 years. Diagnosis of CFRD is made by standard American Diabetes Association (ADA) criteria during baseline health. CFRD can also be diagnosed in individuals with CF during acute illness, while on enteral feeds, and after transplant. In this review we will discuss the epidemiology of CFRD and provide an overview of the advantages and pitfalls of current screening and diagnostic tests for CFRD.

 Dr Swapnil Khare is Assistant Professor of Clinical Medicine in the Division of Endocrinology, Diabetes and Metabolism, Indiana University-Purdue University, Indianapolis, IN, United States.

Lina Merjaneh, Sana Hasan, Nader Kasim, Katie Larson Ode. The role of modulators in cystic fibrosis related diabetes.  J Clin Transl Endocrinol  2021 Dec 7;27:100286. doi: 10.1016/j.jcte.2021.100286.eCollection 2022 Mar.  Free PMC article   [Pubmed]

The development and introduction of modulator therapies have completely shifted the paradigm for the treatment of cystic fibrosis (CF). Highly effective modulator therapies have driven marked improvements in lung function, exacerbation rate, weight and quality of life in CF patients. However, their effect on CF related diabetes (CFRD) is not well delineated. The role of CF transmembrane conductance regulator (CFTR) in CFRD pathogenesis is inadequately understood and research aimed at deciphering the underlying mechanisms of CFRD continues to evolve.

In this review, we summarize what is known regarding the effect of CFTR modulators on CFRD. Small studies using ivacaftor monotherapy in gating mutations have revealed improvement in insulin secretion, glucose tolerance and/or decrease in insulin requirement. However, lumacaftor/ivacaftor studies (primarily in delta F 508 homozygous) have not revealed significant improvement in CFRD or glucose tolerance. No studies are yet available regarding the effect of the highly effective triple therapy (elexacaftor/tezacaftor/ivacaftor) on CFRD or insulin secretion. CFTR modulators might affect development or progression of CFRD through many mechanisms including improving insulin secretion by correcting the CFTR defect directly, improving ductal function, reducing islet inflammation, and improving incretin secretion or by enhancing insulin sensitivity via reduced systemic inflammation and increased physical activity driven by improved lung function and quality of life. On the other hand, they can stimulate appetite and improve gastrointestinal function resulting in increased caloric intake and absorption, driving excessive weight gain and potentially increased insulin resistance. If the defect in insulin secretion is reversible then it is possible that initiation of CFTR modulators at a younger age might help prevent CFRD. Despite the advances in CF management, CFRD remains a challenge and knowledge continues to evolve. Future studies will drive better understanding of the role of highly effective CFTR modulators in CFRD.

Dr Lina Merjaneh is a pediatric endocrinologist and Assistant Professor at Seattle Children’s Hospital.

Amir Moheet , Antoinette Moran. New concepts in the pathogenesis of cystic fibrosis-related diabetes.  J Clin Endocrinol Metab. 2022 Feb 2;dgac020.doi: 10.1210/clinem/dgac020.Online ahead of print. [Pubmed]

Context: Cystic fibrosis related diabetes (CFRD) is the most common extra pulmonary complication of cystic fibrosis (CF). Around 40% of people with CF above age 20 have CFRD. Presence of CFRD is associated with poor health outcomes in people with CF.
Objective: This review summarizes current knowledge on pathophysiology of CFRD.
Methods: A PubMed review of the literature was conducted, and search terms included CFRD, cystic fibrosis, cystic fibrosis related diabetes, and cystic fibrosis transmembrane conductance regulator (CFTR). Additional sources were identified through manual searches of reference lists. The pathophysiology underlying development of glucose tolerance abnormalities in CF is complex and not fully understood. β-cell loss and functional impairment of the remaining β-cell function results in progressive insulin insufficiency. Factors that may contribute to development in CFRD include local islet and systemic inflammation, alterations in the incretion hormone axis, varying degrees of insulin resistance and genetic factors related to type 2 diabetes
Conclusion: The prevalence of CFRD is expected to further increase with improving life expectancy of people with CF. Further research is needed to better understand the mechanisms underlying the development of CFRD and the impact of diabetes on clinical outcomes in CF.

Dr Amir Moheet is in the Department of Medicine, University of Minnesota, Minneapolis, Minnesota
Dr Antoinette Moran is in the Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota

Megan E Gabel, Hongyue Wang, Daniel Gelfond, Christine Roach, Steven M Rowe, John P Clancy, Scott D Sagel, Drucy Borowitz, PROSPECT GIFT Sub-study Investigators of the Cystic Fibrosis Foundation Therapeutics Development Network. Changes in Glucose Breath Test in Cystic Fibrosis Patients Treated with one Month of Lumacaftor/ivacaftor.  J Pediatr Gastroenterol Nutr   2022 Apr 20.doi: 10.1097/MPG.0000000000003459.Online ahead of print.[Pubmed]

Background: Alteration of the airway microbiota is a hallmark of cystic fibrosis (CF) pulmonary disease. Dysfunction of cystic fibrosis transmembrane regulator (CFTR) in the intestine also promotes changes in local microbiota such as small intestinal bacterial overgrowth (SIBO), which is common in CF. We evaluated whether therapy with the CFTR modulator combination lumacaftor/ivacaftor (luma/iva) has a beneficial impact on SIBO as measured by breath testing (BT).
Methods: A multicenter longitudinal study of CFTR-dependent disease profiling (NCT02477319) included a prospective evaluation for SIBO by BT. Tidal breath samples were collected after fasting and 15, 30, 45, 60, 90 and 120 minutes after ingestion of glucose, before and one month after subjects initiated luma + iva.
Results: Forty-two subjects enrolled in the sub-study (mean age = 23.3 years; 51% female; 9.5% Latinx); 38 completed a hydrogen BT at both time points, of which 73.7% had a positive BT prior to luma/iva (baseline) and 65.8% had a positive test after luma/iva (p = 0.44); shifts from negative to positive were also seen. Use of azithromycin (63.1%) and inhaled antibiotics (60.5%) were not associated with positive BT. Acid-blocking medications were taken by 73% of those with a negative BT at baseline and by 35% with a positive baseline BT (p = 0.04).

Conclusion: We found a high rate of positive hydrogen breath tests in individuals with CF, confirming that SIBO is common. One month of luma/iva did not significantly change the proportion of those with positive breath hydrogen measurements.

Megan E Gabel is a pediatric gastroenterologist in the Department of Pediatrics, University of Rochester School of Medicine, Rochester NY.

Insa Korten, Elisabeth Kieninger, Linn Krueger, Marina Bullo, Christa E Flück, Philipp Latzin, Carmen Casaulta, Claudia Boettcher  Short-Term Effects of Elexacaftor/Tezacaftor/Ivacaftor Combination on Glucose Tolerance in Young People With Cystic Fibrosis-An Observational Pilot Study.  Front Pediatr 2022 Apr 21;10:852551.doi: 10.3389/fped.2022.852551. eCollection 2022. [Pubmed]

The effect of elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) on glucose tolerance and/or cystic-fibrosis-related diabetes (CFRD) is not well understood. We performed an observational study on the short-term effects of ELX/TEZ/IVA on glucose tolerance.
Methods: Sixteen adolescents with CF performed oral glucose tolerance tests (OGTT) before and 4-6 weeks after initiating ELX/TEZ/IVA therapy. A continuous glucose monitoring (CGM) system was used 3 days before until 7 days after starting ELX/TEZ/IVA treatment.
Results: OGTT categories improved after initiating ELX/TEZ/IVA therapy (p = 0.02). Glucose levels of OGTT improved at 60, 90, and 120 min (p < 0.05), whereas fasting glucose and CGM measures did not change.

Conclusion: Shortly after initiating ELX/TEZ/IVA therapy, glucose tolerance measured by OGTT improved in people with CF. This pilot study indicates that ELX/TEZ/IVA treatment has beneficial effects on the endocrine pancreatic function and might prevent or at least postpone future CFRD.