Diabetes mellitus in cystic fibrosis

Continuous glucose monitoring systems for monitoring cystic fibrosis-related diabetes

BACKGROUND

Cystic fibrosis (CF) is one of the most common life-shortening autosomal-recessive genetic conditions with around 100,000 people affected globally. CF mainly affects the respiratory system, but cystic fibrosis-related diabetes (CFRD) is a common extrapulmonary co-morbidity and causes excess morbidity and mortality in this population. Continuous glucose monitoring systems (CGMS) are a relatively new technology and, as yet, the impact of these on the monitoring and subsequent management of CFRD remains undetermined.

OBJECTIVES

To establish the impact of insulin therapy guided by continuous glucose monitoring compared to insulin therapy guided by other forms of glucose data collection on the lives of people with CFRD.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. Date of latest search: 23 September 2021. We also searched the reference lists of relevant articles and reviews and online trials registries. Date of last search: 23 September 2021.

SELECTION CRITERIA

Randomised controlled studies comparing insulin regimens led by data from CGMS (including real-time or retrospective data, or both) with insulin regimens guided by abnormal blood glucose measurements collected through other means of glycaemic data collection in people with CFRD. Studies with a cross-over design, even with a washout period between intervention arms, are not eligible for inclusion due to the potential long-term impact of each of the interventions and the potential to compromise the outcomes of the second intervention.

DATA COLLECTION AND ANALYSIS

No studies were included in the review, meaning that no data were available to be collected for analysis.

MAIN RESULTS

Review authors screened 14 studies at the full-text stage against the review's inclusion criteria. Consequently, seven were excluded due to the study type being ineligible (not randomised), two studies were excluded due to their cross-over design, and two studies was excluded since the intervention used was not eligible and one was a literature review. One study in participants hospitalised for a pulmonary exacerbation is ongoing. Investigators are comparing insulin dosing via insulin pump with blood sugar monitoring by a CGMS to conventional diabetes management with daily insulin injections (or on an insulin pump if already on an insulin pump in the outpatient setting) and capillary blood glucose monitoring. The participants in the control arm will wear a blinded continuous glucose monitoring system for outcome assessment. In addition to this, one further study is still awaiting classification, and will be screened to determine whether it is eligible for inclusion, or is to be excluded, in an update of this review.

AUTHORS' CONCLUSIONS

No studies were included in the review, indicating that there is currently insufficient evidence to determine the impact of insulin therapy guided by CGMS compared to insulin therapy guided by other forms of glucose data collection on the lives of people with CFRD, nor on potential adverse effects of continuous glucose monitoring in this context. Randomised controlled studies are needed to generate evidence on the efficacy and safety of continuous glucose monitoring in people with CFRD. There is one relevant ongoing study that may be eligible for inclusion in a future update of this Cochrane Review, and whose results may help answer the review question.

Pregnancy in cystic fibrosis: Review of the literature and expert recommendations

Cystic fibrosis (CF) was historically a disease largely afflicting children. Due to therapeutic advancements, there are now more adults with CF than children. In the past decade, medications including Cystic Fibrosis Transmembrane conductance Regulator (CFTR) modulators became available that treat the underlying cause of CF and are dramatically improving lung function as well as quality and quantity of life for people with CF. As a result, more women with CF are becoming pregnant. We gathered a panel of experts in CF care, family planning, high risk obstetrics, nutrition, genetics and women with CF to review current literature on pregnancies and to provide care recommendations for this unique population.

Insulin secretion abnormalities in exocrine pancreatic sufficient cystic fibrosis patients

BACKGROUND

The aim of this study is to assess insulin secretion in pediatric cystic fibrosis (CF) patients with exocrine pancreatic sufficiency.

METHODS

Glucose and insulin responses during an oral glucose tolerance test (OGTT) were measured in 146 CF patients. Patients were divided into exocrine sufficient (CF-PS) and insufficient (CF-PI) groups based on pancreatic enzyme usage and fecal elastase. A reference group included healthy, non-diabetic subjects.

RESULTS

All CF groups showed reduced insulin secretion as measured by insulinogenic index. The CF-PS patients had normal glucose tolerance. There was a direct correlation between BMI z-score and insulin area under the curve.

CONCLUSION

Patients with CF have reduced insulin secretion during an OGTT regardless of exocrine pancreatic status. The abnormal insulin secretion in all CF patients may predispose them for glucose intolerance, particularly when challenged by inflammation, infection, or nutritional deficiency. In addition, the diminished insulin secretion may contribute to increased catabolism. Lastly, the CF-related diabetes (CFRD) screening guidelines should be followed by all CF patients regardless of pancreatic status.

Hyperglycemia impedes lung bacterial clearance in a murine model of cystic fibrosis-related diabetes

Cystic fibrosis-related diabetes (CFRD) is the most common comorbidity associated with cystic fibrosis (CF), impacting more than half of patients over age 30. CFRD is clinically significant, portending accelerated decline in lung function, more frequent pulmonary exacerbations, and increased mortality. Despite the profound morbidity associated with CFRD, little is known about the underlying CFRD-related pulmonary pathology. Our aim was to develop a murine model of CFRD to explore the hypothesis that elevated glucose in CFRD is associated with reduced lung bacterial clearance. A diabetic phenotype was induced in gut-corrected CF transmembrane conductance regulator (CFTR) knockout mice (CFKO) and their CFTR-expressing wild-type littermates (WT) utilizing streptozotocin. Mice were subsequently challenged with an intratracheal inoculation of Pseudomonas aeruginosa (PAO1) (75 μl of 1-5 × 10(6) cfu/ml) for 18 h. Bronchoalveolar lavage fluid was collected for glucose concentration and cell counts. A portion of the lung was homogenized and cultured as a measure of the remaining viable PAO1 inoculum. Diabetic mice had increased airway glucose compared with nondiabetic mice. The ability to clear bacteria from the lung was significantly reduced in diabetic WT mice and control CFKO mice. Critically, bacterial clearance by diabetic CFKO mice was significantly more diminished compared with nondiabetic CFKO mice, despite an even more robust recruitment of neutrophils to the airways. This finding that CFRD mice boast an exaggerated, but less effective, inflammatory cell response to intratracheal PAO1 challenge presents a novel and useful murine model to help identify therapeutic strategies that promote bacterial clearance in CFRD.

Insulin production and resistance in cystic fibrosis: effect of age, disease activity, and genotype

AIM

To assess the major determinants of glucose tolerance between age, genotype, and clinical status in cystic fibrosis (CF) patients, and study if defects of insulin secretion and insulin sensitivity were associated with the onset of CF-related diabetes (CFRD).

SUBJECTS AND METHODS

One hundred and nineteen patients, in stable clinical condition were studied. They were subdivided into 3 groups based on age, and 2 groups based on Schwachman-Kulczycki clinical score. All patients were genotyped, and subsequently divided into 3 groups. Ninety-four healthy normal-weight controls, comparable for sex and age were also studied. All subjects had baseline blood samples taken for glucose and insulin, C-peptide, and glycated hemoglobin. Homeostasis model assessment of insulin resistance (HOMA-IR), fasting glucose/insulin ratio (FGIR) were calculated as indices of IR and insulinogenic index as a marker of pancreatic β-cell function. All patients underwent an oral glucose tolerance test, and 57 underwent an IVGTT for the calculation of first-phase (FPIR) and acute insulin responses (AIR).

RESULTS

The F508del homozygous patients had an increased chance of developing impaired glucose tolerance (IGT) and significantly lower FPIR, decreased HOMA-IR, and insulinogenic index. Heterozygote F508del patients had an increased chance of having normal glucose tolerance. HOMA-IR, FGIR, and insulinogenic index did not change with age or clinical score. HOMAIR correlated with FPIR. FPIR correlated positively with insulinogenic index. AIR correlated negatively with FGIR, and positively with C-reactive protein. In multiple linear regression analyses, glucose tolerance was related to the agegroup, and to the HOMA-IR and insulinogenic indexes.

CONCLUSIONS

IGT and CFRD were related mainly to genotype, although, as expected, the prevalence increased with age. The data suggested a possible combined contribution of insulin deficiency, β-cell function, and reduced insulin sensitivity to the onset of CFRD; however, further studies are warranted to better elucidate this aspect.

Natural history of glucose intolerance in patients with cystic fibrosis: ten-year prospective observation program

OBJECTIVE

To determine prospectively the long-term natural history of glucose homeostasis in adult patients with cystic fibrosis (CF).

STUDY DESIGN

Between 1996 and 2005, a total of 971 modified oral glucose tolerance tests (OGTTs) were performed in 329 patients with CF without recognized CF-related diabetes (CFRD). Patients were classified as having normal glucose tolerance (NGT), impaired glucose tolerance (IGT), CFRD without fasting hyperglycemia (FH), or CFRD with FH. Data were collected at baseline from the Toronto Cystic Fibrosis database.

RESULTS

On first OGTT, 63% of the 257 patients with pancreatic insufficiency (PI) had NGT, 23% had IGT, 11% had CFRD without FH, and 3% had CFRD with FH. Burkholderia cepacia complex colonization was correlated with worsening glucose tolerance category. There was a weak inverse relationship among weight, body mass index, forced expiratory volume in 1 minute, and 2-hour plasma glucose obtained during OGTT. Of the 168 PI patients who had a second OGTT, 17% improved their category of glucose tolerance, 70% remained unchanged, and 13% worsened. A similar trend was seen during the progression between any one test to a subsequent test.

CONCLUSIONS

Annual screening of glucose tolerance in patients with CF reveals highly variable results over time. Fluctuating levels of insulin resistance, probably with variable degrees of ongoing inflammation, affect the results and hinder prediction of future development of CFRD. Home glucose monitoring following abnormal OGTT results was essential in establishing the diagnosis of CFRD.

Dichotomy between postprandial glucose and lipid profiles in adults with cystic fibrosis: a pilot study

BACKGROUND

Cystic fibrosis (CF) patients present a high incidence of glucose tolerance abnormalities. Altered insulin secretion combined with recommended high-fat intake could be associated with dysregulation of glucose and lipid metabolism. We examined postprandial glucose and lipid profiles during an oral glucose tolerance test (OGTT) and following a standardized high-fat test meal (TM).

METHODS

Sixteen CF patients with normal glucose tolerance (NGT) or CF-related diabetes (CFRD) and 16 controls underwent a 4 h OGTT and a TM. We then measured plasma glucose, insulin, free fatty acid (FFA) and triglyceride (TG) concentrations.

RESULTS

CF patients presented higher glucose excursion compared to controls after the OGTT and TM. However, in CF patients, this excursion was significantly reduced in both amplitude and length after the TM. The TM provoked a comparable increase in TG levels in both groups whereas they remained stable during the OGTT. FFAs were suppressed similarly in both groups after both challenges.

CONCLUSION

CF is associated with abnormal glucose excursion in the presence of relatively normal lipid excursion. The rapid normalization of glucose values after a mixed meal should be further explored and, if confirmed, might have significant implications for CFRD diagnostic.

Diabetes mellitus in patients with cystic fibrosis

Cystic fibrosis-related diabetes (CFRD) is the principal extra-pulmonary complication of cystic fibrosis, occurring in 15-30% of adult cystic fibrosis patients. The number of cystic fibrosis patients who develop diabetes is increasing in parallel with increases in life expectancy. The aim of this study was to review the physiopathology, clinical presentation, diagnosis and treatment of CFRD. A bibliographic search of the Medline and Latin American and Caribbean Health Sciences Literature databases was made. Articles were selected from among those published in the last twenty years. Insulin deficiency, caused by reduced beta-cell mass, is the main etiologic mechanism, although insulin resistance also plays a role. Presenting features of type 1 and type 2 diabetes, CFRD typically affects individuals of approximately 20 years of age. It can also be accompanied by fasting, non-fasting or intermittent hyperglycemia. Glucose intolerance is associated with worsening of nutritional status, increased morbidity, decreased survival and reduced pulmonary function. Microvascular complications are always present, although macrovascular complications are rarely seen. An oral glucose tolerance test is recommended annually for patients > or = 10 years of age and for any patients presenting unexplained weight loss or symptoms of diabetes. Patients hospitalized with severe diseases should also be screened. If fasting hyperglycemia persists for more than 48 h, insulin therapy is recommended. Insulin administration remains the treatment of choice for diabetes and fasting hyperglycemia. Calories should not be restricted, and patients with CFRD should be managed by a multidisciplinary team.

O diabetes melito na fibrose cística: uma comorbidade cada vez mais freqüente

O diabetes melito (DM) é a principal comorbidade relacionada à fibrose cística (FC) e costuma acontecer após os 15 anos de idade, associando-se ao aumento da morbimortalidade. Sua fisiopatologia inclui destruição do tecido exócrino, insuficiência endócrina e aumento da resistência insulínica, determinando inicialmente a alteração da cinética secretora da insulina, até o comprometimento de sua secreção total. A hiperglicemia pós-prandial é a alteração clínica mais precoce e sintomas do DM podem não ser reconhecidos. A investigação anual deve ser realizada por meio da glicemia de jejum ou de glicemias ao acaso e do teste oral de tolerância à glicose (OGTT). São reconhecidas duas categorias de diabetes relacionadas à FC: o DRFC sem hiperglicemia de jejum (HJ) (glicemia de jejum < 126 mg/dL e glicemia de 2 horas OGTT > 200 mg/dL) e DRFC com HJ (glicemia de jejum > 126 mg/dL). O tratamento inclui o manejo nutricional especializado e a correção da hiperglicemia. A insulinoterapia é recomendada para a categoria DRFC com HJ, não existindo ainda evidências do benefício de drogas secretagogas ou sensibilizantes da ação insulínica.

Inpatient Diabetes Mellitus in the Oncology Setting

CASE STUDY

A.B. is a 32-year-old Caucasian man with a significant, 12-year medical history of diabetes mellitus type I as well as a history of hypertension and hypercholesterolemia. He presented to his primary care doctor with blurred vision and was referred to a retinal specialist, who diagnosed hemorhagic and leukemic retinopathy resulting in limited vision. A complete blood count was drawn during the visit with his retinal specialist. The results were abnormal, revealing a white blood cell count of 30,000/mm3, platelet count of 70,000/mm3, and a hemoglobin of 12.2 gm/dl. The peripheral smear showed peripheral blasts. A.B. was referred to a hematologist, who performed a bone marrow aspiration, confirming the diagnosis of pre-B-cell acute lymphocytic leukemia (ALL). Cytogenetic studies revealed positivity for the Philadelphia chromosome and a translocation of genes 4 and 11.

Glucose homeostasis and genotype-phenotype interplay in cystic fibrosis patients with CFTR gene deltaF508 mutation

OBJECTIVE

We sought to determine the clinical phenotype of adolescent/adult patients with cystic fibrosis, according to heterozygosity or homozygosity for cystic fibrosis transmembrane regulator (CFTR) deltaF508 mutation, and to analyze their characteristics according to glucose tolerance status.

RESEARCH DESIGN AND METHODS

A total of 76 cystic fibrosis patients with CFTR deltaF508 mutation (33 heterozygous and 43 homozygous) stratified according to normal glucose tolerance (NGT) (n = 51) or abnormal glucose homeostasis (AGH) (impaired fasting glucose, impaired glucose tolerance, or diabetes; n = 25) had their homeostasis model assessment (HOMA) of beta-cell function and of insulin sensitivity and hyperbolic product (beta-cell function x insulin sensitivity [B x S]) measured. Pancreatic exocrine insufficiency was inferred from pancreatine requirements. Clinical effects of insulin therapy on weight and lung function were recorded.

RESULTS

AGH was observed in 24 and 40% of heterozygous and homozygous subjects, respectively. AGH patients were older than NGT patients (mean +/- SD age 29 +/- 10 vs. 23 +/- 8 years, P = 0.006), and their beta-cell function was lower (93 +/- 49 vs. 125 +/- 51%, P = 0.011). Insulin sensitivity values were comparable in NGT and AGH patients. A lower B x S product was observed in AGH, although it was nonsignificant when adjusted for error propagation. Pancreatic insufficiency was observed in 52 and 100% of heterozygous and homozygous patients (P = 0.001).

CONCLUSIONS

Pre-diabetes and diabetes represent frequent comorbidities in CFTR deltaF508 mutation in the homozygous or heterozygous states. Impairment of insulin secretion, as shown by HOMA, is an important determinant when compared with the magnitude of compensation from insulin sensitivity. Given the high prevalence of abnormal glucose tolerance, screening for (pre-)diabetes is mandatory. Insulin supplementation in diabetic subjects with CFTR deltaF508 mutation seems a rational therapy for consideration, although this does not preclude that therapy directed toward insulin resistance could also interact.

Liver disease as risk factor for cystic fibrosis-related diabetes development

AIM

To evaluate clinical and genetic factors, besides pancreatic insufficiency, associated with increased risk of cystic fibrosis-related diabetes.

METHODS

Case-control (1:1) study on 138 cystic fibrosis patients. Data were collected on gender, age at diagnosis, reason for cystic fibrosis diagnosis, family history of type 1 or 2 diabetes mellitus, pre-existing severe liver disease, and class of cystic fibrosis transmembrane regulation mutation. Moreover, information was obtained on lung involvement and degree of exocrine pancreatic insufficiency evaluated 1 year before the diagnosis of cystic fibrosis-related diabetes in patients and age-matched controls.

RESULTS

Compared to controls, patients with cystic fibrosis-related diabetes had a higher probability of having already been diagnosed with liver disease (16.7% versus 1.7%, OR = 11.6, 95% CI 1.43-93.0). Moreover, in the year before diabetes onset, cases had slightly worse pulmonary function compared to controls (FEV1 = 58.4 +/- 27% predicted versus 67.4 +/- 21% predicted; p = 0.05). No significant effects related to the other factors considered were found.

CONCLUSION

Severe liver disease was found to significantly increase the risk of developing cystic fibrosis-related diabetes. Patients with liver disease should be scheduled for earlier diabetes screening in order to identify and possibly treat glucose intolerance.

Cystic fibrosis transmembrane conductance regulator deficiency exacerbates islet cell dysfunction after beta-cell injury

The cause of cystic fibrosis-related diabetes (CFRD) remains unknown, but cystic fibrosis transmembrane conductance regulator (CFTR) mutations contribute directly to multiple aspects of the cystic fibrosis phenotype. We hypothesized that susceptibility to islet dysfunction in cystic fibrosis is determined by the lack of functional CFTR. To address this, glycemia was assessed in CFTR null (CFTR(-/-)), C57BL/6J, and FVB/NJ mice after streptozotocin (STZ)-induced beta-cell injury. Fasting blood glucose levels were similar among age-matched non-STZ-administered animals, but they were significantly higher in CFTR(-/-) mice 4 weeks after STZ administration (288.4 +/- 97.4, 168.4 +/- 35.9, and 188.0 +/- 42.3 mg/dl for CFTR(-/-), C57BL/6J, and FVB/NJ, respectively; P < 0.05). After intraperitoneal glucose administration, elevated blood glucose levels were also observed in STZ-administered CFTR(-/-) mice. STZ reduced islets among all strains; however, only CFTR(-/-) mice demonstrated a negative correlation between islet number and fasting blood glucose (P = 0.02). To determine whether a second alteration associated with cystic fibrosis (i.e., airway inflammation) could impact glucose control, animals were challenged with Aspergillus fumigatus. The A. fumigatus-sensitized CFTR(-/-) mice demonstrated similar fasting and stimulated glucose responses in comparison to nonsensitized animals. These studies suggest metabolic derangements in CFRD originate from an islet dysfunction inherent to the CFTR(-/-) state.

Insulin versus oral agents in the management of Cystic Fibrosis Related Diabetes: a case based study

BACKGROUND

Insulin is the recommend therapeutic agent of choice for the management of Cystic Fibrosis Related Diabetes (CFRD), despite only sub-optimal reductions in glycemic control and increased morbidity and mortality reported by centers using this agent. The newer insulin sensitizing agents demonstrated to have anti-inflammatory mechanisms may provide an alternative management option for CFRD.

METHODS

A prospective case based therapeutic comparison between insulin, sulfonylurea, metformin and thiazolidinedione was observed over one decade with 20 CFRD patients diagnosed using American Diabetes Association guideline standards. Patients entering the study elected treatment based on risk and benefit information provided for treatment options. Patients receiving organ transplant or requiring combination diabetic medications were excluded from the study.

RESULTS

No statistical advantage was achieved regarding overall glycemic control for oral agents over insulin. Additional outcome measures including changes in weight, liver function testing and FEV1 were not statistically significant.

CONCLUSION

Insulin alone may not be the only therapeutic option in managing CFRD. Oral hypoglycemic agents were equally effective in treating CFRD and may provide an alternative class of agents for patients reluctant in using insulin.

Mild to moderate cystic fibrosis is not associated with increased fracture risk in children and adolescents

OBJECTIVES

To determine whether children and adolescents with cystic fibrosis (CF), pancreatic insufficiency (PI), and mild-to-moderate lung disease have an increased risk of fracture compared with concurrent healthy control subjects.

STUDY DESIGN

A lifetime fracture history questionnaire was administered to 186 subjects (ages 6 to 25 years) with CF, PI and mild-to-moderate lung disease and 427 healthy white control subjects (ages 4 to 25 years).

RESULTS

A fracture was reported by 24% of subjects with CF and 23% of healthy control subjects. Average age of first fracture was similar between the groups (8.3 years for subjects and 8.8 years for controls). The radius/ulna was the most common fracture site in both groups. Risk of fracture, adjusted for sex and age, was not greater in the CF group compared with the control group (hazard ratio: 0.96, 95% CI: 0.68, 1.30, P = .82).

CONCLUSION

Children and adolescents with CF, PI, and mild-to-moderate lung disease were not at an increased risk of fracture.

Continuous glucose monitoring in adolescents with cystic fibrosis

The presence of cystic fibrosis (CF)-related diabetes was evaluated in 19 adolescents with CF by continuous glucose monitoring system (CGMS) and oral glucose tolerance testing. CGMS confirmed diabetic glucose excursions in 7/19 subjects deemed diabetic on oral glucose tolerance testing. CGMS is a useful tool for detecting hyperglycemia in CF.

Diabetes: a major co-morbidity of cystic fibrosis

Cystic fibrosis-related diabetes (CFRD) is a frequent complication of cystic fibrosis, its prevalence increases with age of patient and is close to 30% at the age of 30 years. As life expectancy greatly increases, the number of cystic fibrosis patients developing diabetes will increase too. CFRD shares some features with type 1 and type 2 diabetes, initial phase is characterised by postprandial hyperglycaemia followed by a progression toward insulin deficiency. Insulin deficiency is an essential factor in the development of diabetes with an additional contribution of insulin resistance. Systematic screening with an oral glucose tolerance test is recommended from the age of 14 years because clinical signs of CFRD are often confused with signs of pulmonary infection and CFRD occurrence is associated with weight and pulmonary function deterioration. In observational studies CFRD diagnosis is associated with a significant increase in mortality, while treatment allow correction of weight and lung deterioration suggesting that CFRD has a significant impact on CF evolution. Microvascular complications are recognised, although paucity of data does not permit a clear description of their natural history. Annual screening for microvascular complication is recommended. There is no evidence by now that CF patients develop macrovascular complications. The only recommended pharmacological treatment is insulin therapy.

Roles for bone-marrow-derived cells in beta-cell maintenance

With more than 177 million people suffering from diabetes worldwide, and the number expected to double by 2030, finding new ways to treat this disease is a high priority. Intensive effort is being directed towards developing mechanisms for increasing beta-cell expansion as a diabetic therapeutic. Recent studies, in which adult bone marrow has been used to induce beta-cell expansion in mice, have shown both exciting and controversial results. In these reports, marrow-derived cells can contribute towards beta-cell maintenance both by promoting endogenous beta-cell expansion and possibly by transdifferentiation into beta-cells. These studies reveal mechanisms for potential therapeutic intervention.

Insulin-secretion abnormalities and clinical deterioration related to impaired glucose tolerance in cystic fibrosis

OBJECTIVE

To evaluate insulin-secretion kinetics and insulin sensitivity in cystic fibrosis (CF) patients with normal glucose tolerance (CF-NGT), impaired glucose tolerance (CF-IGT) or CF-related diabetes (CFRD), and the potential effects of moderate hyperglycemia on clinical and nutritional status.

DESIGN AND METHODS

Cross-sectional study including 50 outpatients with CF. Patients underwent both oral (OGGT) and intravenous (IVGTT) glucose tolerance tests in order to assess insulin secretion and peripheral insulin sensitivity. Homeostasis assessment model and OGGT were used to investigate insulin sensitivity. Forced expiratory volume in the first second (FEV(1)) and forced vital capacity (FVC) were measured to evaluate pulmonary function. Body mass index (BMI) was determined to assess nutritional status.

RESULTS

Insulin secretion was significantly decreased (and delayed at OGTT) in the CFRD group (n = 9) versus the CF-IGT group (n = 10) and the CF-IGT versus the CF-NGT group (n = 31). Insulin sensitivity was significantly different in the CF-IGT and CFRD groups versus the CF-NGT group. FEV(1), FVC and BMI presented a significant linear correlation with plasma glucose value at 120 min at OGTT and were significantly lower in both CF-IGT and CFRD versus the CF-NGT group, whereas no differences were found between the CF-IGT and CFRD groups.

CONCLUSIONS

CF patients with IGT present diminished insulin secretion and increased peripheral insulin resistance, correlating with a worse clinical status, undernutrition and impaired pulmonary function. These findings open the question of whether early treatment of mild alterations of glucose metabolism with insulin secretagogues or short-action insulin may lead to improvement of clinical status in CF patients.

Cystic fibrosis presenting as new onset diabetes mellitus in adolescent twins

We describe identical adolescent twin girls who 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.

Cystic fibrosis-related diabetes

Diabetes mellitus (DM) has been recognized as a complication of cystic fibrosis (CF) for almost 50 years and commonly develops around 20 years of age. The prevalence increases with age and, with improved survival of those with CF, approaches 30% in certain centres. Its development appears to have a significant impact on pulmonary function and may increase mortality by up to six-fold. Subjects with CF are rarely ketosis-prone and phenotypically lie between Type 1 and Type 2 DM. Microvascular complications are recognized, although paucity of data does not permit a clear description of their natural history. An annual oral glucose tolerance test from the age of 10 years is recommended for screening, but logistical difficulties have led some groups to develop specific algorithms to aid diagnosis. Insulin sensitivity in CF is much debated and may depend upon the degree of glucose intolerance. Insulin resistance occurs in the presence of infection, corticosteroid usage and hyperglycaemia, whilst hepatic insulin resistance is considered an adaptation to CF. There is no universal consensus on the treatment of hyperglycaemia. With increased longevity of individuals with CF, greater numbers will develop diabetes and the diabetes physician is destined to play a greater role in the multidisciplinary CF team.

Diagnosis, screening, and management of cystic fibrosis-related diabetes

Diabetes is a common complication of cystic fibrosis (CF), occurring in approximately 40% of adult patients. It is clinically distinct from type 1 or type 2 diabetes, and requires a unique approach. Because of evidence that it is associated with increased morbidity and mortality, prompt diagnosis and aggressive management of CF-related diabetes (CFRD) is important. The Cystic Fibrosis Foundation held a consensus conference in 1998 to define the current standards for the diagnosis and care of this disease. This article reviews those recommendations, and presents a practical approach to the management of CFRD.