New criteria for impaired fasting glucose and screening for diabetes in cystic fibrosis

Cystic fibrosis related diabetes (CFRD) in the era of modulators: A scoping review

Cystic fibrosis-related diabetes (CFRD) is a common complication of CF that increases in incidence as patients age. Poor glycemic control has been shown to negatively impact lung function and weight, resulting in higher risk of recurrent pulmonary exacerbations. With the advent of highly effective modulator therapies (HEMT), patients with CF are living longer and healthier lives. Consequently, CFRD and its microvascular complications are rising in prominence, becoming one of the most urgent clinical concerns. As HEMT were developed with the primary focus of improving pulmonary outcomes, it is not clear from the original phase III studies what the short- or long-term benefits of modulators might be on CFRD development and trajectory. In this review, we will examine the pathophysiology of CFRD, summarize and synthesize the available evidence of HEMT impact on CFRD and describe the emerging research needs in this field.

Marginal association of fasting blood glucose with the risk of cystic fibrosis-related diabetes

OBJECTIVES

Cystic fibrosis-related diabetes (CFRD) may be diagnosed by fasting blood glucose ≥ 7.0 mmol/L and/or glucose ≥ 11.1 mmol/L following oral glucose tolerance test (OGTT). We compared the role of fasting and stimulated glucose for diagnosis of CFRD.

METHODS

We performed a cross-sectional review of the prevalence of fasting glycemic abnormalities and Kaplan-Meier survival analysis of risk of progression to CFRD according to baseline fasting glucose in the prospective Montreal Cystic Fibrosis Cohort.

RESULTS

Isolated fasting hyperglycemia was detected in only 8% of participants at study onset. Eighty percent of subjects had isolated post-challenge hyperglycemia on their first OGTT meeting criteria for CFRD. Kaplan Meier survival analysis demonstrated that impaired fasting glucose (IFG) alone is not a risk factor for CFRD. Subjects with combined IFG and impaired glucose tolerance at baseline (IGT) had the highest risk of progression to CFRD.

CONCLUSION

Post-prandial elevations in blood glucose are more common at diagnosis of CFRD. While IGT is a significant risk factor for CFRD, IFG alone is uncommon and does not increase the risk of CFRD. Patients with both IGT and IFG have the highest risk of CFRD.

Diabetes and Prediabetes in Children With Cystic Fibrosis: A Systematic Review of the Literature and Recommendations of the Italian Society for Pediatric Endocrinology and Diabetes (ISPED)

Cystic fibrosis related diabetes (CFRD) is a comorbidity of cystic fibrosis (CF) that negatively impacts on its clinical course. Prediabetes is an important predictor of either CFRD development and unfavorable prognosis of CF in both pediatric and adult patients. International guidelines recommend insulin only in case of CFRD diagnosis. Whether early detection and treatment of prediabetes may contribute to improve the clinical course of CF is still debated. A subgroup of pediatric diabetologists of the Italian Society for Pediatric Endocrinology and Diabetology (ISPED) performed a systematic review of the literature based on predefined outcomes: impact of pre-diabetes on clinical outcomes and on the risk of developing CFRD; diagnosis of diabetes and pre-diabetes under 10 years of age; effectiveness of therapy on glycemic control, impact of therapy on pulmonary function and nutritional status. Thirty-one papers were selected for the analysis data presented in these papers were reported in tables sorted by outcomes, including comprehensive evidence grading according to the GRADE approach. Following the grading of the quality of the evidence, the entire ISPED diabetes study group achieved consensus for the Italian recommendations based on both evidence and clinical experience. We concluded that in patients with CF, prediabetes should be carefully considered as it can evolve into CFRD. In patients with CF and prediabetic conditions, after complete evaluation of the OGTT trend, glucometrics, glycemic values measured during pulmonary exacerbations and/or steroid therapy, early initiation of insulin therapy could have beneficial effects on clinical outcomes of patients with CF and prediabetes.

Fasting blood glucose levels in patients with different types of diseases

Normal human physiology is dependent on a tight control of the fasting blood glucose (FBG) levels. The islets of pancreas maintains FBG levels within a narrow range of 4-6mmol/L by secreting various hormones, especially insulin and glucagon. However, the hormone secretions by the islets of pancreas are governed by a collective effort among pancreas-islet axis, brain-islet axis, liver-islet axis, gut-islet axis, and adipocyte/myocyte-islet axis. Furthermore, the damage of pancreas, vascular system, brain, liver, intestine, adipose, muscle, and other organs and tissues might affect FBG levels through insulin resistance or impaired insulin signaling, which is the hallmark of type 2 diabetes. In this study, 320,572 clinical lab test results of FBG levels from healthy individuals and patients with 64 different types of diseases during the past 5 years in our hospital were retrieved and analyzed. Based on the mean (SD), median, and p (-Log₁₀p) values, we found 57/64 diseases including type 2 diabetes, pancreatitis, diabetic nephropathy, and pancreatic cancer had significantly (p<0.05, -Log₁₀p>1.30) increased whereas 6/64 diseases including preeclampsia, Wilms' tumor, and lupus erythematous had significantly decreased FBG levels compared to that of healthy controls. These data indicated that the increased FBG levels might be a general pathophysiological property of diseased tissues or organs and the increased FBG levels might be a consequence but not the cause for either prediabetes or type 2 diabetes.

Repaglinide versus insulin for newly diagnosed diabetes in patients with cystic fibrosis: a multicentre, open-label, randomised trial

BACKGROUND

As survival among patients with cystic fibrosis has improved in recent decades, complications have become increasingly relevant. The most frequent complication is cystic-fibrosis-related diabetes. The recommended treatment is injected insulin, but some patients are treated with oral antidiabetic drugs to ease the treatment burden. We assessed the efficacy and safety of oral antidiabetic drugs.

METHODS

We did 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. We used a central randomisation schedule derived from a Geigy random number table to assign patients 1:1 to receive insulin or repaglinide, stratified by sex and age (10-15 years or >15 years). The primary outcome was glycaemic control assessed by mean change in HbA_1c concentration from baseline after 24 months of treatment. Differences between groups were assessed by linear models. The primary and safety analyses were done in the modified intention-to-treat population (including patients who stopped treatment early because of lack of efficacy). This trial is registered with ClinicalTrials.gov, number NCT00662714.

FINDINGS

We enrolled 34 patients 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_1c concentration 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).

INTERPRETATION

Repaglinide for glycaemic control in patients with cystic-fibrosis-related diabetes is as efficacious and safe as insulin.

FUNDING

Mukoviszidose eV, Vaincre la Mucoviscidose, ABCF Association, and Novo Nordisk.

Cystic Fibrosis-Related Diabetes

Cystic fibrosis (CF) is the most common autosomal recessive disorder in Caucasian populations. Individuals with CF have seen significant increases in life expectancy in the last 60 years. As a result, previously rare complications are now coming to light. The most common of these is cystic fibrosis-related diabetes (CFRD), which affects 40-50% of CF adults. CFRD significantly impacts the pulmonary function and longevity of CF patients, yet a lack of consensus on the best methods to diagnose and treat CFRD remains. We begin by reviewing our understanding of the pathogenesis of CFRD, as emerging evidence shows the cystic fibrosis transmembrane conductance regulator (CFTR) also has important roles in the release of insulin and glucagon and in the protection of β cells from oxidative stress. We then discuss how current recommended methods of CFRD diagnosis are not appropriate, as continuous glucose monitoring becomes more effective, practical, and cost-effective. Finally, we evaluate emerging treatments which have narrowed the mortality gap within the CF patient group. In the future, pharmacological potentiators and correctors directly targeting CFTR show huge promise for both CFRD and the wider CF patient groups.

HbA1c as a screening tool for cystic fibrosis related diabetes

AIMS

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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%.

Lifestyle interventions for adults with impaired glucose tolerance: a systematic review and meta-analysis of the effects on glycemic control

OBJECTIVE

Previous meta-analyses have demonstrated that lifestyle modification can reduce the blood glucose levels in patients with type 2 diabetes, although the effects of changes in the blood glucose level on impaired glucose tolerance (IGT) remain controversial. This review therefore aimed to determine the efficacy of lifestyle interventions in adults with IGT.

METHODS

We searched the Medline, Cochrane Library, EMBASE and Science Citation Index databases and reference lists of the included articles. Two independent reviewers extracted the data and assessed the quality of the included studies; a total of nine randomized controlled trials met the inclusion criteria. In addition, we tested for trial heterogeneity and calculated the pooled effects size using the random effects model.

RESULTS

The overall interventions were associated with a decline in the 2-hour plasma glucose levels [standardized mean differences (SMD) -0.56; 95% confidence interval (CI), -1.01 to -0.10; I(2), 96.6%]. Moreover, dietary intervention (SMD -0.53; 95% CI -0.77 to -0.28) and physical intervention (SMD -0.42; 95% CI -0.63 to -0.20) were each associated with a decline in the 2-hour plasma glucose levels compared with that observed in the control participants. The overall interventions were associated with a decline in the fasting plasma glucose (FPG) levels (SMD -0.27; 95% CI -0.38 to -0.15; I(2) = 47.1%). In addition, physical intervention (SMD -0.25; 95% CI -0.44 to -0.05) and combined dietary and physical intervention were each associated with a decreased FPG level (SMD -0.28; 95% CI -0.44 to -0.12) compared with that observed in the control participants.

CONCLUSION

Lifestyle modification based on physical or dietary interventions or both is associated with improvements in the 2-hour plasma glucose and FPG levels in IGT patients.

Cystic fibrosis related diabetes

Improved life expectancy in cystic fibrosis (CF) has led to an expanding population of adults with CF, now representing almost 50 % of the total CF population. This creates new challenges from long-term complications such as diabetes mellitus (DM), a condition that is present in 40 %-50 % of adults with CF. Cystic fibrosis-related diabetes (CFRD) results from a primary defect of insulin deficiency and although sharing features with type 1 (DM1) and type 2 diabetes (DM2), it is a clinically distinct condition. Progression to diabetes is associated with poorer CF clinical outcomes and increased mortality. CFRD is not associated with an increased risk of cardiovascular disease and the prevalence of microvascular complications is lower than DM1 or DM2. Rather, the primary goal of insulin therapy is the preservation of lung function and optimization of nutritional status. There is increasing evidence that appropriate screening and early intervention with insulin can reverse weight loss and improve pulmonary function. This approach may include targeting postprandial hyperglycemia not detected by standard diagnostic tests such as the oral glucose tolerance test. Further clinical research is required to guide when and how much to intervene in patients who are already dealing with the burden of one chronic illness.

Open randomised prospective comparative multi-centre intervention study of patients with cystic fibrosis and early diagnosed diabetes mellitus

BACKGROUND

Diabetes mellitus may be present in patients with cystic fibrosis starting in the second decade of life. The prevalence increases rapidly with increasing age. As life-expectancy increases in cystic fibrosis, cystic fibrosis related diabetes will be diagnosed more frequently in the future.Up to date, no data are available to answer the question if cystic fibrosis related diabetes should always initially be treated by insulin therapy. Missing data regarding oral antidiabetic treatment of newly diagnosed cystic fibrosis related diabetes are an important reason to recommend insulin treatment. Several centres report the successful management of cystic fibrosis related diabetes using oral anti-diabetic drugs at least for some years. Oral therapies would be less invasive for a patient group which is highly traumatized by a very demanding therapy. Based on an initiative of the German Mukoviszidosis-Foundation, the present study tries to answer the question, whether oral therapy with repaglinide is as effective as insulin therapy in cystic fibrosis patients with early diagnosed diabetes mellitus.

METHODS/DESIGN

In all cystic fibrosis patients with an age of 10 years or older, an oral glucose tolerance test is recommended. The result of this test is classified according to the WHO cut off values. It is required to have two diabetes positive oral glucose tolerance tests for the diagnosis of diabetes mellitus.This study is a multi-national, multicentre, open labelled, randomized and prospective controlled parallel group's trial, with 24 months treatment.The primary objective of this trial is to compare the glycaemic control of oral therapy with Repaglinide with insulin injections in patients with cystic fibrosis related diabetes after 2 years of treatment.The trial should include 74 subjects showing cystic fibrosis related diabetes newly diagnosed by oral glucose tolerance test during annual screening for cystic fibrosis related diabetes.Patients are randomised by central fax randomisation.Primary endpoint is mean HbA1c after 24 months of treatment. Secondary endpoints are change in FEV1% predicted and change in BMI-Z-score.

DISCUSSION

There is only one prospective study comparing oral antidiabetic drugs to insulin in the treatment of CFRD without fasting hyperglycaemia. The results regarding BMI after 6 months and 12 months showed an improvement for the insulin treated patients and were inconsistent for those treated with repaglinide. HbA1c and lung function (FEV1%pred) were unchanged for either group. The authors compared the changes -12 months to baseline and baseline to +12 months separately for each group. Therefore a direct comparison of the effect of repaglinide versus insulin on BMI, HbA1c and FEV1%pred was not presented. According to our protocol, we will directly compare treatment effects (HbA1c, BMI, FEV1%pred) in between both groups. The actual Cochrane report regarding "Insulin and oral agents for managing CFRD" stated that further studies are needed to establish whether there is clear benefit for hypoglycemic agents. We expect that the results of our study will help to address this clinical need.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00662714.

Diabetes in cystic fibrosis: multicenter screening results based on current guidelines

BACKGROUND

Published estimates on age-dependent frequency of diabetes in cystic fibrosis (CF) vary widely, and are based mostly on older data. However, CF treatment and prevention of comorbidities changed over recent years. In many studies, definition of cystic fibrosis-related diabetes (CFRD) is not in line with current guideline recommendations. Therefore, we evaluated age-dependent occurrence of glucose abnormalities and associated risk factors in CF patients who participated in a multicenter screening program using oral glucose tolerance tests (OGTT).

METHODS

Between 2001 and 2010, 43 specialized CF centers from Germany and Austria serially performed 5,179 standardized OGTTs in 1,658 clinically stable, non-pregnant CF patients with no prior steroid medication or lung transplantation. Age-dependent occurrence of impaired fasting glucose (IFG), impaired glucose tolerance (IGT), IFG+IGT, one (DGT) or two consecutive (CFRD) diabetic OGTTs was analyzed, using Kaplan Meier curves. Cox proportional-hazards models were created to elucidate the influence of sex or underweight.

RESULTS

At baseline/last OGTT, median age was 15.9 years/18.2 years and 30.6%/31.8% of patients were underweight. 25% of patients showed IFG at age 14.3 years; IGT at age 16.3 years; IFG+IGT combined at age 17.7 years. DGT was observed in 25% of patients at age 22.6 years; CFRD at age 34.5 years. Females had a 3.54 [95% CI 1.23-10.18] times higher risk for CFRD; risk for DGT was 2.21 [1.22-3.98] times higher. Underweight was a risk factor for IGT (HR [95% CI]: 1.38 [1.11-1.71]) and IFG+IGT (1.43 [1.11-1.83]), and in males also for DGT (1.49 [1.09-2.04]).

CONCLUSIONS/SIGNIFICANCE

If confirmation of diabetes by a second test is required, as recommended in current guidelines, age at CFRD diagnosis was higher compared to most previous studies. However, known risk factors for glucose abnormalities in CF were confirmed. Confirmation of diabetic OGT by a repeat test is important for a consistent diagnosis of CFRD.

The complex exocrine-endocrine relationship and secondary diabetes in exocrine pancreatic disorders

The pancreas is a dual organ with exocrine and endocrine functions. The interrelationship of the endocrine-exocrine parts of the pancreas is a complex one, but recent clinical and experimental studies have expanded our knowledge. Many disorders primarily of the exocrine pancreas, often solely in the clinical realm of gastroenterologists are associated with diabetes mellitus (DM). Although, the DM becoming disorders are often grouped with type 2 diabetes, the pathogenesis, clinical manifestations and management differ. We review here data on the association of exocrine-endocrine pancreas, the many hormones of the pancreas and their possible effects on the exocrine functions followed by data on the epidemiology, pathogenesis, and management of DM in chronic pancreatitis, cystic fibrosis, pancreatic cancer, and clinical states after pancreatic surgery.

Impaired fasting glucose in cystic fibrosis

OBJECTIVE

While glucose tolerance abnormalities are common in cystic fibrosis (CF), impaired fasting glucose (IFG) has scarcely been explored. No studies have examined the relation between IFG and clinical status.

RESEARCH DESIGN AND METHODS

Data were retrieved from the University of Minnesota CF database on oral glucose tolerance tests (OGTTs) performed in 1996-2005. Subjects were identified as normal glucose tolerance (NGT), impaired glucose tolerance (IGT), or CF-related diabetes without fasting hyperglycemia (CFRD FH-). Patients with fasting hyperglycemia were excluded. The presence of IFG was assessed within each category. In a separate case-control cohort study, subjects with IFG were matched to CF control subjects by age, sex, and OGTT class to explore outcomes.

RESULTS

For the total population (n = 310), the prevalence of IFG was 22%, and by OGTT class was NGT 14%, IGT 31%, CFRD FH- 53%. Within the cohort study, mortality was significantly reduced in IFG (two vs. nine deaths, odds ratio [OR] = 0.2 [95% CI 0.04-0.9]). IFG did not confer increased risk of progression to diabetes (OR 0.66 [0.29-1.48]). Lung function was better in pediatric IFG subjects with IGT and not significantly worse in adults with IGT or adults and children with NGT and CFRD FH-. BMI was not significantly different in IFG subjects versus control subjects.

CONCLUSIONS

Contrary to expectations in patients with CF, IFG appeared to be associated with improved survival and was not associated with worse nutritional or pulmonary status or increased progression to fasting hyperglycemia.

Lack of correlation between 1,5-anhydroglucitol assay and oral glucose tolerance test in patients with cystic fibrosis

OBJECTIVE

To determine whether the 1,5-anhydroglucitol (1,5-AG) assay, which reflects serum glucose levels during the preceding 2 weeks, could be used as an alternative to the current standard screening test for cystic fibrosis-related diabetes (CFRD)-the oral glucose tolerance test (OGTT).

METHODS

Serum 1,5-AG, hemoglobin A1c (A1C), fructosamine, and glucose at various time intervals during the OGTT were measured in 10 patients, 19 to 36 years old, with cystic fibrosis. Correlation coefficients were calculated to compare 1,5-AG with A1C, fructosamine, and serum glucose levels during the OGTT, and the mean 1,5-AG, A1C, and fructosamine for normal glucose tolerance, impaired glucose tolerance (IGT), and CFRD were compared statistically.

RESULTS

On the basis of the 120-minute OGTT, 1 of the 10 study subjects had CFRD and 4 had IGT. The mean 1,5-AG for patients with normal glucose tolerance was not significantly different from that for patients with IGT (P = .063). The 1,5-AG value was not significantly correlated with serum glucose during the OGTT, A1C, or fructosamine.

CONCLUSION

In this pilot study, we found no significant correlation between 1,5-AG and glucose values during the OGTT or between 1,5-AG and other glycemic markers. Hence, the utility of the 1,5-AG assay for screening for CFRD in the population of patients with cystic fibrosis may be limited.

Growth in children with cystic fibrosis-related diabetes

Cystic fibrosis-related diabetes (CFRD) is associated with a shortened life expectancy and greater deterioration in lung function than in CF patients with normal glucose metabolism. There are few published data on how CFRD affects growth in childhood. We carried out a retrospective case controlled study of growth and lung function in 34 children with CFRD attending three specialist centers in London. We found that for the 2 years leading to CFRD diagnosis (at a mean age of 13.1 years), the mean height velocity was significantly less compared to controls: 4.9 (standard deviation-SD 1.6) cm/year vs. 6.0 (SD 1.9) cm/year (P = 0.005). For the 2 years following diagnosis, height velocity remained significantly lower (3.4 (SD 2.2) cm/year vs. 4.4 (SD 2.2) cm/year, P = 0.02). Mean FEV(1) was reduced prior to diagnosis and at diagnosis, but was similar to controls 2 years after diagnosis. This study highlights the compromise in height velocity and lung function that occurs prior to diagnosis of CFRD in children with CF, and a reduction in height velocity should be considered an indicator of impaired glucose metabolism. It would be useful to know whether early treatment with insulin can help promote catch up growth.

[Value of continuous glucose monitoring in screening for diabetes in cystic fibrosis]

AIMS

In the past few years, survival has increased for people with cystic fibrosis (CF). Diabetes is an important complication of CF caused by pancreatic insufficiency, which reduces insulin secretion. Because of increased longevity of patients with CF, the prevalence of CF-related diabetes (CFRD) has increased. CFRD is associated with increased mortality and morbidity. Several studies have reported a decline in nutritional and pulmonary status 2-4 years before the diagnosis of CFRD. The introduction of insulin treatment can produce clinical improvement in weight and lung function. The oral glucose tolerance test is currently the reference method in screening for CFRD, but the current definition of diabetes based on the 2-h post-load plasma glucose level may not be the most accurate method for early detection of glucose tolerance abnormalities in CF. The continuous glucose monitoring system (CGMS) has been described as a useful tool for early detection of hyperglycemia in the CF patient. We tested the CGMS in CF patients with unexplained alteration of their general status. The aim of this study was to assess the value of the CGMS in this population.

METHODS

An annual OGTT (following World Health Organization recommendations) was conducted as a screening test to identify CFRD in patients aged over 10 years or patients aged under 10 years with a poorer clinical status. The CGMS was performed in patients with unexplained worsened clinical status and without diabetes in OGTT.

RESULTS

Forty-two patients aged from 8.5 to 19 years were screened using OGTT for CFRD. According to ADA criteria, 23 patients (54.8%) displayed normal glucose tolerance, 14 (33.3%) impaired glucose tolerance, and 5 diabetes (11.9%). Out of 37 nondiabetic, the CGMS was used in 20 patients with unexplained altered general status. The CGMS revealed peaks of glucose values greater than 2 g/L in 16 patients, 9 patients with normal glucose tolerance, and 7 patients with impaired glucose tolerance. The mean CGMS glucose and time of glycemic monitoring above 1.4 g/L increased in patients with peaks greater than 2 g/L compared to patients without peaks (p=0.0016 and p=0.0069 respectively). After analysis of the CGMS, the prevalence of diabetes increased from 11.9 to 50%. Three patients aged less than 10 years with a normal OGTT profile presented glycemic peaks greater than 2 g/L during CGMS.

CONCLUSION

CGMS revealed more glucose metabolism abnormalities than OGTT in patients with unexplained altered general status.

Symposium 6: Young people, artificial nutrition and transitional care The nutritional challenges of the young adult with cystic fibrosis: transition

Cystic fibrosis (CF) is a complex multisystem disorder affecting mainly the gastrointestinal tract and respiratory system. Intestinal malabsorption occurs in approximately 90% of patients. In the past, malnutrition was an inevitable consequence of disease progression, leading to poor growth, impaired respiratory muscle function, decreased exercise tolerance and immunological impairment. A positive association between body weight and height and survival has been widely reported. The energy requirements of patients with CF vary widely and generally increase with age and disease severity. For many young adults requirements will be 120–150% of the age-related estimated average requirement. To meet these energy needs patients are encouraged to eat a high-fat high-energy diet with appropriate pancreatic enzyme supplements. Many patients are unable to achieve an adequate intake as a result of a variety of factors including chronic poor appetite, infection-related anorexia, gastro-oesophageal reflux and abdominal pain. Oral energy supplements and enteral tube feeding are widely used. Nutritional support has been shown to improve nutritional status and stabilise or slow the rate of decline in lung function. With such emphasis on nutritional intake and nutritional status throughout life, poor adherence to therapies and issues relating to body image are emerging. The median survival of patients with CF is increasing. CF is now considered a life-limiting disease of adulthood rather than a terminal childhood illness. With increased longevity new challenges are emerging that include the transition of young adults with CF to adult services, CF-related diabetes, disordered eating, osteoporosis, liver disease and transplantation.

[Continuous glucose monitoring system in the screening of glucose disorders in cystic fibrosis]

BACKGROUND

Diabetes mellitus (DM) is an increasing complication of cystic fibrosis (CF). It is associated with enhance morbidity. Continuous glucose monitoring system (CGMS) could detect glucose disorders earlier than other screening tests usually used.

AIMS

To compare oral glucose tolerance test (OGTT), HbA(1c) and CGMS in patients with CF and recent disorders of glucose homeostasis and to analyse changes in nutritional status and/or pulmonary function.

PATIENTS AND METHODS

Thirteen patients with CF (11-22 years, 7 males) were studied using OGTT, HbA(1c) and CGMS. All of them had newly diagnosed glucose disturbances. They were not receiving steroid therapy or had an underlying illness. In all subjects we compared: HbA(1c) levels (%), fasting and 2-hours glucose OGTT (mg/dl) and glucose CGMS values (overall, fasting, 2-hours post mean-meals and excursions >140mg/dl at any time). Furthermore, body mass index, forced expiratory volume in the first second (%) and forced vital capacity (%) were evaluated in the previous year and at the time of the study. We also analysed exocrine pancreatic function and CF-mutation.

RESULTS

Mean age at diagnosis of glucose disturbance was 16.4 years. All patients had insufficient exocrine pancreatic function and 11/13 presented DeltaF508 CF-mutation. Only one patient was diagnosed with DM using OGGT and 7/13 (53.8%) with CGMS. A total 77% of patients had poor nutritional status and/or pulmonary function at time of diagnosing the glucose disorder. Only 4 patients had abnormal HbA(1c) levels.

CONCLUSIONS

CGMS allows a better detection of glucose disorders than OGTT. Glucose homeostasis abnormalities are associated with a decrease in nutritional status and/or pulmonary function. HbA(1c) does not aid in the early diagnose of glucose disorders.

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.

Glucose tolerance, insulin secretion, and insulin sensitivity in children and adolescents with cystic fibrosis and no prior history of diabetes

OBJECTIVE

To determine the prevalence of abnormalities of glucose metabolism in pediatric outpatients with cystic fibrosis (CF).

STUDY DESIGN

Children and adolescents (n = 73, mean age 15.0 +/- 3.7 years) with CF not previously diagnosed with diabetes underwent 3-hour oral glucose tolerance testing. All subjects with CF were clinically stable and were not being treated for active infection. A reference group of young lean adults was used for comparison. Subjects were classified as having normal glucose tolerance (NGT) or abnormal glucose metabolism (AGM), including impaired glucose tolerance (IGT), impaired fasting glucose (IFG), or diabetes, by standard criteria. The insulinogenic index was calculated as a measure of beta-cell function, and insulin resistance was estimated with the homeostatic model assessment.

RESULTS

The reference group was significantly older than the patients with CF, but in the control subjects, the AGM and NGT were comparable in body mass index z-scores (-0.8 +/- 1.3, -0.6 +/- 1.1, -0.21 +/- 0.9 kg/m2). Thirty-eight percent of subjects with CF had AGM: 43% IGT, 29% IFG, 14% IGT/IFG, and 14% diabetes. In spite of distinct differences in glycemic response, the subjects with NGT and AGM had marked abnormalities of insulin secretion relative to the control subjects (Insulinogenic index 5.8 +/- 1.0, 5.3 +/- 0.8, and 53.5 +/- 10.0 uU/mL/mmol/L, respectively; P < .0001). Insulin sensitivity did not differ among the 3 groups, although there was a trend toward greater insulin resistance in the subjects with AGM (homeostatic model assessment: CF-NGT 1.5 +/- 0.2, CF-AGM 1.9 +/- 0.3, REF 1.3 +/- 0.1, P = NS).

CONCLUSION

Abnormalities in glucose metabolism are frequent in young patients with CF without a prior diagnosis of diabetes and are associated with marked defects in insulin secretion. Given the poor beta-cell function in patients with CF, even small reductions in insulin sensitivity may be an important determinant of AGM.

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.