One-year glargine treatment can improve the course of lung disease in children and adolescents with cystic fibrosis and early glucose derangements

Exogenous insulin does not reduce protein catabolism in pre-diabetic cystic fibrosis patients: A randomized clinical trial

BACKGROUND

Cystic Fibrosis (CF) patients historically suffered from undernutrition, infection and inflammation. Insulin insufficiency-related protein catabolism further compromised health. We aimed to determine whether insulin improves protein catabolism in CF youth with abnormal glucose tolerance (AGT).

METHODS

This double-masked, placebo-controlled trial in CF youth age 10-25 with AGT who were in their usual state of health used triple-tracer stable-isotope methodology to measure protein turnover during a baseline test meal and after four weeks of insulin/placebo treatment. Healthy controls were assessed once. CF patients were randomized 1:1:1 to once-daily long-acting insulin (0.25 U/kg/d), three-times daily rapid-acting insulin (0.5 U/15gr carbohydrate), or injectable placebo.

RESULTS

Thirty CF patients completed the study. There were no differences in any measure of protein turnover between insulin- and placebo-treated subjects, including endogenous protein breakdown (primary study endpoint). In contrast to earlier studies, protein turnover in the 37 CF patients who completed the baseline meal was normal compared to 20 healthy controls. Meal isotope appeared in plasma earlier in CF than controls, suggesting more rapid gut emptying. The study was interrupted by the pandemic; futility analysis led to study discontinuation before the planned remaining 15 CF patients were studied.

CONCLUSIONS

Recent advances in CF have led to remarkable clinical improvements. In this study, CF youth with AGT had normal protein catabolism at baseline. Pre-meal or daily basal insulin therapy, while safe and well tolerated, did not significantly enhance protein turnover and does not appear to be necessary in clinically stable patients prior to development of CFRD.

Effects of insulin therapy optimization with sensor augmented pumps on glycemic control and body composition in people with cystic fibrosis-related diabetes

Objective

Cystic fibrosis (CF)-related diabetes (CFRD) resulting from partial-to-complete insulin deficiency occurs in 40-50% of adults with CF. In people with CFRD, poor glycemic control leads to a catabolic state that may aggravate CF-induced nutritional impairment and loss of muscle mass. Sensor augmented pump (SAP) therapy may improve glycemic control as compared to multiple daily injection (MDI) therapy.

Research design and methods

This non-randomized clinical trial was aimed at evaluating the effects of insulin therapy optimization with SAP therapy, combined with a structured educational program, on glycemic control and body composition in individuals with insulin-requiring CFRD. Of 46 participants who were offered to switch from MDI to SAP therapy, 20 accepted and 26 continued the MDI therapy. Baseline demographic and clinical characteristics were balanced between groups using a propensity score-based overlap weighting procedure and weighted mixed-effects regression models were used to estimate changes in study outcomes.

Results

After 24 months changes in HbA1c were: -1.1% (-12.1 mmol/mol) (95% CI: -1.5; -0.8) and -0.1% (-1 mmol/mol) (95% CI: -0.5; 0.3) in the SAP and MDI therapy group, respectively, with a between-group difference of -1.0 (-10 mmol/mol) (-1.5; -0.5). SAP therapy was also associated with a decrease in mean glucose (between group difference: -32 mg/dL; 95% CI: -44; -20) and an increase in TIR (between group difference: 19.3%; 95% CI 13.9; 24.7) and in fat-free mass (between group difference: +5.5 Kg, 95% CI: 3.2; 7.8).

Conclusion

Therapy optimization with SAP led to a significant improvement in glycemic control, which was associated with an increase in fat-free mass.

Continuous Glucose Monitoring as an Additional Tool in Early Cystic Fibrosis-Related Diabetes Monitoring and in Evaluation of Short-Term Sitagliptin Response

Cystic fibrosis-related diabetes (CFRD) is a complication associated with a negative prognosis in patients with cystic fibrosis (CF). Although the oral glucose tolerance test (OGTT) is the widely recommended screening test for CFRD diagnosis, continuous glucose monitoring (CGM) is increasingly considered a useful and easy-to-perform test for diagnosis and follow-up in clinical practice. Regarding CFRD treatment, although insulin is the classic approved pharmacological option, incretins could also be a helpful alternative in early stages. CGM could be also a useful tool to measure the early response to this therapy.

METHODS

We studied 25 CF patients with abnormal OGTT results and compared glucose and insulin levels during the OGTTs with CGM results as a tool for early CFRD diagnosis. In addition, we evaluated glycaemic control with CGM before and after treatment with sitagliptin.

RESULTS

A correlation was found between lower plasma insulin levels during the OGTTs and higher average sensor glucose (p = 0.009) and hyperglycaemic excursions (p = 0.017). The CGM data on sitagliptin treatment (n = 25) showed an average glycaemic improvement from 124.2 to 117.2 mg/dL (p = 0.002) with a 5.6-point standard deviation of glucose decrease (p < 0.001). Hyperglycaemic excursions ≥200 mg/dL diminished 57.1% (p = 0.021). Both time in range and time above 180 mg/dL improved during treatment (p = 0.036 and p = 0.006, respectively).

CONCLUSION

CGM is a useful tool that offers valuable information for both the diagnosis and the management of CFRD. Lower plasma insulin levels during OGTTs are associated with a poor ambulatory glucose profile in CGM. Sitagliptin could play an important role in the treatment of the early stages of CFRD.

Comparison of continuous glucose monitoring to reference standard oral glucose tolerance test for the detection of dysglycemia in cystic Fibrosis: A systematic review

Aims

Increasing evidence for benefit of early detection of cystic fibrosis related diabetes (CFRD) coupled with limitations of current diagnostic investigations has led to interest and utilisation of continuous glucose monitoring (CGM). We conducted a systematic review to assess current evidence on CGM compared to reference standard oral glucose tolerance test for the detection of dysglycemia in people with cystic fibrosis without confirmed diabetes.

Methods

MEDLINE, Embase, CENTRAL, Evidence-Based Medicine Reviews, grey literature and six relevant journals were searched for studies published after year 2000. Studies reporting contemporaneous CGM metrics and oral glucose tolerance test results were included. Outcomes on oral glucose tolerance tests were categorised into a) normal, b) abnormal (indeterminate and impaired) or c) diabetic as defined by American Diabetes Association criteria. CGM outcomes were defined as hyperglycemia (≥1 peak sensor glucose ≥ 200 mg/dL), dysglycemia (≥1 peak sensor glucose ≥ 140-199 mg/dL) or normoglycemia (all sensor glucose peaks < 140 mg/dL). CGM hyperglycemia in people with normal or abnormal glucose tolerances was used to define an arbitrary CGM-diagnosis of diabetes. The Quality Assessment of Diagnostic Accuracy Studies tool was used to assess risk of bias. Primary outcome was relative risk of an arbitrary CGM-diagnosis of diabetes compared to the oral glucose tolerance test.

Results

We identified 1277 publications, of which 19 studies were eligible comprising total of 416 individuals with contemporaneous CGM and oral glucose tolerance test results. Relative risk of an arbitrary CGM-diagnosis of diabetes compared to oral glucose tolerance test was 2.92. Studies analysed were highly heterogenous, prone to bias and inadequately assessed longitudinal associations between CGM and relevant disease-specific sequela.

Conclusions

A single reading > 200 mg/dL on CGM is not appropriate for the diagnosis of CFRD. Prospective studies correlating CGM metrics to disease-specific outcomes are needed to determine appropriate cut-points.

Endocrine Complications of Cystic Fibrosis

Endocrine comorbidities have become increasingly important medical considerations as improving cystic fibrosis (CF) care increases life expectancy. Although the underlying pathophysiology of CF-related diabetes remains elusive, the use of novel technologies and therapeutics seeks to improve both CF-related outcomes and quality of life. Improvements in the overall health of those with CF have tempered concerns about pubertal delay and short stature; however, other comorbidities such as hypogonadism and bone disease are increasingly recognized. Following the introduction of highly effective modulator therapies there are many lessons to be learned about their long-term impact on endocrine comorbidities.

Continuous Glucose Monitoring and HbA1c in Cystic Fibrosis: Clinical Correlations and Implications for CFRD Diagnosis

CONTEXT

The clinical utility and implications of continuous glucose monitoring (CGM) in cystic fibrosis (CF) are unclear.

OBJECTIVE

We examined the correlation between CGM measures and clinical outcomes in adults with CF, investigated the relationship between hemoglobin A1c (HbA1c) and CGM-derived average glucose (AG), and explored CGM measures that distinguish cystic fibrosis-related diabetes (CFRD) from normal and abnormal glucose tolerance.

METHODS

This prospective observational study included 77 adults with CF who had CGM and HbA1c measured at 2 to 3 time points 3 months apart.

RESULTS

Thirty-one of the 77 participants met American Diabetes Association-recommended diagnostic criteria for CFRD by oral glucose tolerance testing and/or HbA1c. In all participants, CGM measures of hyperglycemia and glycemic variability correlated with nutritional status and pulmonary function. HbA1c was correlated with AG (R2 = 0.71, P < 0.001), with no significant difference between this regression line and that previously established in type 1 and type 2 diabetes and healthy volunteers. Cutoffs of 17.5% time > 140 mg/dL and 3.4% time > 180 mg/dL had sensitivities of 87% and 90%, respectively, and specificities of 95%, for identifying CFRD. Area under the curve and percent of participants correctly classified with CFRD were higher for AG, SD, % time > 140, > 180, and > 250 mg/dL than for HbA1c.

CONCLUSION

CGM measures of hyperglycemia and glycemic variability are superior to HbA1c in distinguishing those with and without CFRD. CGM-derived AG is strongly correlated with HbA1c in adults with CF, with a similar relationship to other diabetes populations. Future studies are needed to investigate CGM as a diagnostic and screening tool for CFRD.

Resistance Training Recommendations for Children and Adolescents With Cystic Fibrosis-Related Diabetes

Cystic fibrosis (CF) is the most prevalent hereditary life-threatening disease in the Caucasian population. With the improvement in clinical care, individuals with CF are living longer, and CF-related diabetes (CFRD) has emerged as a major complication. The diagnosis of CFRD is associated with shortening survival, increasing morbidity, worsening physical capacity, and body composition. Engagement in exercise training has become a prominent nonpharmacologic intervention that aims to improve fitness and clinical outcomes in individuals with CF and CFRD. This column will specifically focus on the potential benefits of resistance training and provide recommendations for children and adolescents with CF and CFRD.

Impaired glucose tolerance and indeterminate glycemia in cystic fibrosis

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Oral glucose tolerance testing is used for screening, diagnosis, and risk stratification of cystic fibrosis related diabetes.

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Abnormal glucose tolerance in cystic fibrosis has prognostic utility with regards to progression towards overt diabetes, pulmonary function, weight loss, and mortality.

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Further research is needed to delineate the significance of impaired glucose tolerance and indeterminate glycemia within the CF population.

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Lower thresholds for indeterminate glycemia may be needed within the cystic fibrosis population.

Oral glucose tolerance testing (OGTT) is the primary method to screen for and diagnose cystic fibrosis-related diabetes (CFRD). Diagnostic thresholds as currently defined are based on microvascular complications seen in type 2 diabetes. Abnormal glucose tolerance (AGT) refers to OGTT glucose elevations outside the normal range and encompasses both impaired and indeterminate glucose tolerance. Current guidelines define impaired glucose tolerance (IGT) as a 2-hour glucose of 140–199 mg/dL (7.8–11 mmol/L) and indeterminate glucose tolerance (INDET) as any mid-OGTT glucose ≥ 200 mg/dL (11.1 mmol/L) with a normal fasting and 2 h glucose. There is growing evidence that AGT also has associations with CF-centered outcomes including pulmonary decline, hospitalizations, and weight loss. Here we aim to review the historical emergence of glucose tolerance testing, review relevance to risk stratification for CFRD, discuss alternate cutoffs for identifying AGT earlier, and highlight the need for larger, future studies to inform our understanding of the implications of IGT and INDET on CF health.

Diabetes outbreak during COVID19 lock-down in a prediabetic patient with cystic fibrosis long treated with glargine

BACKGROUND

Cystic Fibrosis Related Diabetes (CFRD) is a frequent comorbidity of patients with Cystic Fibrosis (CF). A worsening of clinical conditions appears before CFRD. It has been demonstrated a decline in pulmonary function and nutritional status also in patients with prediabetes. Few trials show that insulin may be beneficial in prediabetic CF patients, to date guidelines do not recommend for this condition.

CASE PRESENTATION

We report a case of a patient treated with insulin glargine at 13 years, due to glycemic intolerance, and with Lumacaftor/Ivacaftor at 15 years. A reduction of pulmonary exacerbations was observed after glargine therapy, also confirmed after the starting of Lumacaftor/ Ivacaftor in this patient. Pulmonary function improved only after the first year of glargine therapy, then a deterioration appeared due to the natural history of CF lung damage. During the COVID-19 lockdown, poor adherence to care contributed to diabetes mellitus onset needing high insulin requirements. After two weeks the patient returned to prediabetic condition and his previous dose of glargine.

CONCLUSIONS

our case highlights firstly that insulin glargine has contributed to preserve him from further clinical worsening due to prediabetes in the years before pandemic, secondly the negative impact of COVID-19 lockdown on the clinical course of a chronic disease as CF.

Use of hemoglobin A1c to identify dysglycemia in cystic fibrosis

Background

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.

Objective

To determine whether HbA1c is an appropriate screening tool for identifying patients with pre-CFRD dysglycemia to minimize the burden of annual OGTTs.

Methods

This retrospective review evaluated medical records data of all University of Massachusetts Memorial Health System CF patients with an HbA1c result within 90 days of an OGTT between 1997 and 2019. Exclusion criteria were uncertain CF diagnosis, other forms of diabetes, or incomplete OGTT. In total, 56 patients were included and categorized according to OGTT results (American Diabetes Association criteria): normal glucose tolerance, INDET, IFG, or IGT. Associations were evaluated between HbA1c and OGTT results and between HbA1c and pre-CFRD dysglycemic states.

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).

Conclusion

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.

Continuous glucose monitoring indices predict poor FEV1 recovery following cystic fibrosis pulmonary exacerbations

BACKGROUND

Little is known about the effect of dysglycemia during cystic fibrosis pulmonary exacerbation (PEx) on recovery of FEV₁ percentage predicted (ppFEV₁) METHODS: Continuous glucose monitoring (CGM) was commenced at the time of admission to hospital for PEx and continued for 6 weeks. The CGM indices, percentage of time glucose greater than 7.8 mmol/L (%T>7.8) and mean glucose were evaluated as predictors of absolute ppFEV₁ change following treatment of PEx.

RESULTS

Of the 20 participants who completed the study 13 (65%) had cystic fibrosis related diabetes (CFRD). The mean of both CGM indices were highest during the first week of pulmonary exacerbation and continued to decline over the first 4 weeks at which point they plateaued. Using multivariate regression models, factors which were predictive of maximum attained ppFEV₁ change over 6 weeks were %T>7.8, mean glucose, HbA1c and preadmission ppFEV₁ change from baseline. These relationships were independent of a diagnosis of CFRD, which was not associated with ppFEV₁ recovery. In a longitudinal model of ppFEV₁ change at weeks 1, 2 and 6, the CGM index %T>7.8 approached significance as a predictive variable.

CONCLUSIONS

Hyperglycemia during PEx in adult CF patients is associated with poorer ppFEV₁ recovery. Conversely, there was no association observed between CFRD diagnosis and ppFEV₁ improvement, suggesting that optimization of glycemic control in CFRD patients may positively influence recovery of lung function. Further clinical trials are required to evaluate the merits of intensive glycemic control in CFRD during PEx.

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.

Continuous glucose monitoring in cystic fibrosis - A practical guide

Our ability to monitor blood glucose levels has become increasingly accurate over the last few decades. Continuous glucose monitoring (CGM) technology now allows providers and patients the ability to monitor glucose levels retrospectively as well as in real-time for diabetes management. CGM also provides the ability to study glucose patterns and trends for insight into the pathophysiology and natural history of disease. CGM captures a more complete picture of glucose profiles than traditional measures of glycemia such as the hemoglobin A1c or self-monitoring of blood glucose levels. This article provides a review of the history of glucose monitoring, a review of the literature pertaining to CGM with a focus on studies in patients with cystic fibrosis, and discusses practical uses of CGM technology and its application for the evaluation and management of cystic fibrosis related diabetes.

Hypoglycemia in cystic fibrosis: Prevalence, impact and treatment

Hypoglycemia is a common and feared complication of insulin therapy. As in type 1 and type 2 diabetes, people with cystic fibrosis related diabetes are also at risk for hypoglycemia related to insulin therapy. Spontaneous hypoglycemia is also common in patients with CF without diabetes, who are not on glucose lowering medications. Spontaneous hypoglycemia in CF may also occur during or after an oral glucose tolerance test. In this review, we will discuss the definition, epidemiology, pathophysiology and impact of hypoglycemia, with a focus on people with cystic fibrosis. We will also review strategies to manage and prevent hypoglycemia.

Diabetic lung disease: fact or fiction?

Diabetes mellitus is a chronic, progressive, incompletely understood metabolic disorder whose prevalence has been increasing steadily worldwide. Even though little attention has been paid to lung disorders in the context of diabetes, its prevalence has recently been challenged by newer studies of disease development. In this review, we summarize and discuss the role of diabetes mellitus involved in the progression of pulmonary diseases, with the main focus on pulmonary fibrosis, which represents a chronic and progressive disease with high mortality and limited therapeutic options.

Automated glycemic control with the bionic pancreas in cystic fibrosis-related diabetes: A pilot study

Cystic fibrosis-related diabetes (CFRD) is the most common extrapulmonary manifestation of cystic fibrosis. The current standard of care for CFRD involves treatment with insulin, typically via multiple daily injections. We conducted a small pilot study comparing usual care with automated glycemic control using the bihormonal (insulin and glucagon) and insulin-only configurations of the bionic pancreas. Both configurations of the bionic pancreas achieved good glycemic control, with mean glucose levels <150 mg/dl and minimal hypoglycemia. Subjects reported improved treatment satisfaction and reduced burden of diabetes management with the bionic pancreas. Further investigation of automated glycemic control in the treatment of CFRD is warranted.

Exenatide corrects postprandial hyperglycaemia in young people with cystic fibrosis and impaired glucose tolerance: A randomized crossover trial

Impaired glucose tolerance (IGT) in cystic fibrosis (CF) manifests as postprandial hyperglycaemia. Pancreatic enzyme supplementation reduces the latter; restoring incretin secretion and slowing gastric emptying. We aimed to determine the acute effect of exenatide on postprandial glycaemia in young people with CF and IGT. Six participants with CF and IGT were studied on 2 days, in a double-blind randomized crossover trial. After overnight fasting, they received exenatide 2.5 mcg or placebo (0.9% saline) subcutaneously 15 minutes before a pancake meal labelled with 13 C octanoate and pancreatic enzyme replacement. The primary outcomes, area under the curve over 240 minutes (AUC 240 ) for blood glucose (P < 0.0001) and peak blood glucose (7.65 mM ± 0.34 [mean ± SE] vs 9.53 mM ± 0.63, P < 0.0001), were markedly lower after exenatide than placebo. AUC240 for insulin, C-peptide, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) was also lower after exenatide. Gastric emptying was markedly slower after exenatide, as assessed by time for 10% gastric emptying and peak 13 CO2 excretion. We report for the first time that exenatide corrects postprandial hyperglycaemia in young people with CF and IGT. GLP-1 agonists are a candidate treatment in CF-related diabetes.

Continuous glucose monitoring to evaluate glycaemic abnormalities in cystic fibrosis

OBJECTIVE

This study aimed to determine the glycaemic profile of patients with cystic fibrosis using a continuous glucose monitoring system (CGMS), and to evaluate the associations of glycaemic abnormalities with sex, age, pubertal stage, CFTR gene mutations, nutritional status, lung function, oral glucose tolerance test, glycated haemoglobin concentrations, fasting insulin concentrations, C peptide concentrations and exocrine pancreatic function.

STUDY DESIGN

This observational study evaluated CGMS data from 39 patients with cystic fibrosis who were treated at a referral centre. The patients were 10-19.9 years old, and were categorised according to whether they had normal results (27 patients) or glucose intolerance (12 patients) during the oral glucose tolerance test.

RESULTS

The maximum interstitial glucose concentration among individuals with normal oral glucose tolerance test results was 174.9±65.1 mg/dL (9.7-3.61 mmol/L), compared with 170.4±40.9 mg/dL (9.46-2.27 mmol/L) among individuals with glucose intolerance. The CGMS revealed that 18 of the 27 patients with normal oral glucose tolerance test results had peak interstitial glucose concentrations of >140 mg/dL (7.8 mmol/L), and that 4 of these individuals had peak levels of >200 mg/dL (11.1 mmol/L). None of the analysed clinical or laboratory characteristics predicted the occurrence of hyperglycaemic peaks on CGMS.

CONCLUSIONS

The present study revealed that CGMS could detect hyperglycaemia among patients with cystic fibrosis and 'normal' oral glucose tolerance test results, and that their clinical and laboratory characteristics were not useful in discerning between patients who did and did not exhibit these excursions.

Targeting postprandial glycaemia in children with diabetes: Opportunities and challenges

Postprandial glycaemia makes a substantial contribution to overall glycaemic control in diabetes, particularly in patients whose preprandial glycaemia is relatively well controlled and glycated haemoglobin (HbA1c) only modestly elevated. Our review addresses the determinants of postprandial glycaemia and how it may be targeted therapeutically in children with diabetes. Postprandial glycaemia is influenced by preprandial glycaemia, macronutrients and their absorption, insulin delivery and sensitivity, the action of the enteroendocrine system, and the rate of gastric emptying. Contemporary continuous glucose monitoring systems reveal patterns of post prandial glycaemia and allow management to be guided more precisely. Delays in blood glucose determination, insulin delivery and its absorption remain challenges in the rapidly evolving closed loop continuous subcutaneous insulin and glucagon delivery systems developed for children with type 1 diabetes. Augmentation of the incretin system through nutritional preloads or incretin mimetics targets postprandial glycaemia by slowing gastric emptying as well as insulinotropic and glucagonostatic effects. These treatments are of particular relevance to children with type 2 diabetes. Following the development of targeted therapies in adults, postprandial blood glucose control will now be increasingly targeted in the treatment of diabetes in children.

Evolving Mechanistic Views and Emerging Therapeutic Strategies for Cystic Fibrosis-Related Diabetes

Diabetes is a common and important complication of cystic fibrosis, an autosomal recessive genetic disease due to mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Cystic fibrosis-related diabetes (CFRD) is associated with profound detrimental effects on the disease course and mortality and is expected to increase in prevalence as the survival of patients with cystic fibrosis continues to improve. Despite progress in the functional characterization of CFTR molecular defects, the mechanistic basis of CFRD is not well understood, in part because of the relative inaccessibility of the pancreatic tissue and the limited availability of representative animal models. This review presents a concise overview of the current understanding of CFRD pathogenesis and provides a cutting-edge update on novel findings from human and animal studies. Potential contributions from paracrine mechanisms and β-cell compensatory mechanisms are highlighted, as well as functional β-cell and α-cell defects, incretin defects, exocrine pancreatic insufficiency, and loss of islet cell mass. State-of-the-art and emerging treatment options are explored, including advances in insulin administration, CFTR modulators, cell replacement, gene replacement, and gene editing therapies.

Insulin therapy in patients with cystic fibrosis in the pre-diabetes stage: a systematic review

Objective:

To elucidate whether insulin is effective or not in patients with cystic fibrosis before the diabetes mellitus phase.

Data source:

The study was performed according to the Prisma method between August and September 2014, using the PubMed, Embase, Lilacs and SciELO databases. Prospective studies published in English, Portuguese and Spanish from 2002 to 2014, evaluating the effect of insulin on weight parameters, body mass index and pulmonary function in patients with cystic fibrosis, with a mean age of 17.37 years before the diabetes mellitus phase were included.

Data synthesis:

Eight articles were identified that included 180 patients undergoing insulin use. Sample size ranged from 4 to 54 patients, with a mean age ranging from 12.4 to 28 years. The type of follow-up, time of insulin use, the dose and implementation schedule were very heterogeneous between studies.

Conclusions:

There are theoretical reasons to believe that insulin has a beneficial effect in the studied population. The different methods and populations assessed in the studies do not allow us to state whether early insulin therapy should or should not be carried out in patients with cystic fibrosis prior to the diagnosis of diabetes. Therefore, studies with larger samples and insulin use standardization are required.

Cystic Fibrosis-Related Diabetes in Children: An Update

Cystic fibrosis-related diabetes mellitus (CFRD) is the most common endocrine complication of cystic fibrosis (CF), affecting more than 50% of patients by the 4th decade of life. CFRD is often preceded by worsening pulmonary status and nutritional decline. Treatment of CFRD is associated with improvements in body weight and pulmonary function and a reduction in pulmonary exacerbations. Because of the clinical significance of CFRD, diabetes screening with an oral glucose tolerance test (OGTT) is recommended annually for all patients with CF starting at age 10 years. The OGTT detects CFRD with greater sensitivity than random glucose or hemoglobin A1c testing. The first-line treatment for CFRD is insulin. The use of other treatments such as oral medications remains under study. [Pediatr Ann. 2016;45(9):e321-e326.].

The 1-h oral glucose tolerance test glucose and insulin values are associated with markers of clinical deterioration in cystic fibrosis

AIMS

Cystic fibrosis (CF) is associated with the emergence of CF-related diabetes (CFRD). CFRD is associated with increased risk of accelerated weight and/or lung function loss (clinical degradation). Data in the CF pediatric population reported an association between higher 60-min oral glucose tolerance test (OGTT) plasma glucose values and reduced lung function. Our objective was to evaluate the relationship between the 60-min OGTT insulin and glucose values and markers of clinical degradation in adult patients with CF.

METHODS

This study was based on an ongoing observational cohort of CF adult patients (≥18 years). All patients underwent a 2-h OGTT with 30-min interval sample measurements. Plasma insulin and glucose levels were measured. Adult patients (N = 240) were categorized based on the 60-min OGTT median values of glucose (G60, 11.0 mmol/L) and/or insulin (I60, 43.4 μU/mL).

RESULTS

A negative association was observed between the 60-min OGTT glucose value and pulmonary function (FEV1; P = 0.001), whereas 60-min OGTT insulin values were positively associated with BMI (P = 0.004). Patients with high G60 values displayed lower FEV1 than patients with low G60 values (P = 0.025). Patients with higher I60 values demonstrated higher values of both FEV1 (P = 0.022) and BMI (P = 0.003) than patients with low I60 values. More importantly, when adjusting for BMI, the difference in FEV1 between both groups no longer existed (P = 0.166).

CONCLUSIONS

Both insulin and glucose values at 60-min OGTT are associated with indicators of clinical degradation in adult patients with CF. Future prospective analyses are essential in establishing the clinical utility of these indicators.

Insulin therapy in patients with cystic fibrosis in the pre-diabetes stage: a systematic review

OBJECTIVE

To elucidate whether insulin is effective or not in patients with cystic fibrosis before the diabetes mellitus phase.

DATA SOURCE

The study was performed according to the Prisma method between August and September 2014, using the PubMed, Embase, Lilacs and SciELO databases. Prospective studies published in English, Portuguese and Spanish from 2002 to 2014, evaluating the effect of insulin on weight parameters, body mass index and pulmonary function in patients with cystic fibrosis, with a mean age of 17.37 years before the diabetes mellitus phase were included.

DATA SYNTHESIS

Eight articles were identified that included 180 patients undergoing insulin use. Sample size ranged from 4 to 54 patients, with a mean age ranging from 12.4 to 28 years. The type of follow-up, time of insulin use, the dose and implementation schedule were very heterogeneous between studies.

CONCLUSIONS

There are theoretical reasons to believe that insulin has a beneficial effect in the studied population. The different methods and populations assessed in the studies do not allow us to state whether early insulin therapy should or should not be carried out in patients with cystic fibrosis prior to the diagnosis of diabetes. Therefore, studies with larger samples and insulin use standardization are required.

Management of pancreatogenic diabetes: challenges and solutions

Pancreatogenic diabetes is an underdiagnosed form of secondary diabetes that is lacking official management guidelines. This paper reviews the recommended management strategies with additional data on the promising novel drugs.

Glucose >200 mg/dL during Continuous Glucose Monitoring Identifies Adult Patients at Risk for Development of Cystic Fibrosis Related Diabetes

Rationale. Cystic fibrosis related diabetes (CFRD) is the most common comorbidity in patients with CF. In spite of increased screening, diagnosis, and treatment of CFRD, the mortality rate in patients with CFRD still far exceeds the mortality rate in those without CFRD. 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. Objectives. Our 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. Methods. 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. Conclusions. 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).

Glucose intolerance in cystic fibrosis as a determinant of pulmonary function and clinical status

BACKGROUND

Cystic fibrosis related diabetes (CFRD) is associated with a decrease in pulmonary function and nutritional status. We investigated the clinical significance of impaired glucose tolerance (IGT) in cystic fibrosis (CF) patients.

METHODS

Fifty-five CF patients (aged 22.8 ± 9.2 years, 29 males, mean FEV1 67.9 ± 22% predicted, mean BMI-SDS -0.23 ± 1.1) underwent a 2-h Oral Glucose Tolerance Test (OGTT) with 30-min interval measurements of glucose and insulin. Additional clinical and laboratory data were obtained from the medical charts.

RESULTS

Thirty-eight participants (69%) had normal glucose tolerance (NGT), 13 (23.7%) had IGT, and 4 (7.3%) had newly diagnosed CFRD. Compared to patients with NGT, patients with IGT had significantly lower BMI-SDS (-1.1 ± 0.8 vs. 0.1 ± 1.1, p<0.001), mean FEV1 (57 ± 19 vs. 74 ± 21% predicted, p<0.01), and albumin (3.9 ± 0.3 vs. 4.3 ± 0.2g/dl, p=0.004), and higher fibrinogen (376 ± 56 vs. 327 ± 48 g/dl, p=0.02). Patients with IGT had impaired β-cell function, with reduced first phase insulin secretion, a delayed insulin peak, and significantly lower total insulin secretion, HOMA-%B and insulinogenic index. Seven patients had HbA1c in the "diabetic" range (≥6.5%; 47.5 mmol/mol), however, HbA1c was not a sensitive or specific marker of glucose tolerance status.

CONCLUSIONS

IGT in CF patients is associated with increased inflammation and decreased nutritional status and pulmonary function.

Screening of glucose metabolism derangements in pediatric cystic fibrosis patients: how, when, why

Diabetes mellitus is the most common comorbidity in cystic fibrosis (CF), occurring in a variable number of children and adolescents. Glucose metabolism derangements (GMDs) are responsible for a negative impact on the general health status of CF patients. Screening of GMDs is important since the youngest age and should be performed by means of OGTT, including its intermediate times, that could detect other non-traditional GMDs. Insulin treatment, administered before overt diabetes, could be beneficial in reducing the number of pulmonary infections, in improving both pulmonary function and nutritional status. Early screening of GMDs in pediatric age can exert an important preventing role regarding all aspects of health status of patients with CF.

Advances in the detection and management of cystic fibrosis related diabetes

PURPOSE OF REVIEW

This review will outline the screening, diagnosis and management of cystic fibrosis related diabetes (CFRD). It will also discuss advances in the detection of early glucose abnormalities, their clinical significance and the emerging role for early insulin therapy.

RECENT FINDINGS

Before the onset of diabetes (as currently defined), patients with cystic fibrosis (CF) display glucose abnormalities, detectable either by 30-minutely sampled oral glucose tolerance testing (OGTT), or by continuous ambulatory interstitial glucose monitoring (CGM). These early glucose abnormalities are associated with the presence of glucose in airway fluid, potentially promoting the growth of airway pathogens and contributing to the progression of respiratory disease. Progressive insulin deficiency underlies these glucose abnormalities, and insulin deficiency also causes catabolism. Pilot studies of once-daily insulin therapy in the early stages of insulin deficiency show improved lung function and weight gain (important predictors of survival in CF).

SUMMARY

Early stages of insulin deficiency may be contributing to catabolism and deteriorating lung function in CF. It is plausible that early insulin therapy may prevent this deterioration, a view supported by pilot studies. Randomized controlled trials of early insulin therapy will now determine whether insulin therapy should be commenced earlier than current practice in CF.

Management of endocrine disease: Cystic fibrosis-related diabetes: novel pathogenic insights opening new therapeutic avenues

Cystic fibrosis (CF) is a recessive genetic disease caused by mutations in the CF transmembrane conductance regulator (CFTR). CFTR is primarily present in epithelial cells of the airways, intestine and in cells with exocrine and endocrine functions. Mutations in the gene encoding the channel protein complex (CFTR) cause alterations in the ionic composition of secretions from the lung, gastrointestinal tract, liver, and also the pancreas. CF-related diabetes (CFRD), the most common complication of CF, has a major detrimental impact on pulmonary function, nutrition and survival. Glucose derangements in CF seem to start from early infancy and, even when the pathophysiology is multifactorial, insulin insufficiency is clearly a major component. Consistently, recent evidence has confirmed that CFTR is an important regulator of insulin secretion by islet β-cells. In addition, several other mechanisms were also recognized from cellular and animals models also contributing to either β-cell mass reduction or β-cell malfunction. Understanding such mechanisms is crucial for the development of the so-called 'transformational' therapies in CF, including the preservation of insulin secretion. Innovative therapeutic approaches aim to modify specific CFTR mutant proteins or positively modulate their function. CFTR modulators have recently shown in vitro capacity to enhance insulin secretion and thereby potential clinical utility in CFDR, including synergistic effects between corrector and potentiator drugs. The introduction of incretins and the optimization of exocrine pancreatic replacement complete the number of therapeutic options of CFRD besides early diagnosis and implementation of insulin therapy. This review focuses on the recently identified pathogenic mechanisms leading to CFRD relevant for the development of novel pharmacological avenues in CFRD therapy.

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.

New insights into cystic fibrosis-related diabetes in children

Cystic fibrosis-related diabetes (CFRD) is the most common complication of cystic fibrosis. It is associated with significantly increased morbidity and mortality in adults and children. Adolescents with cystic fibrosis have a much higher prevalence of diabetes than any other similar age population. Glucose abnormalities that precede diabetes are even more common, especially in children younger than 10 years. The pathophysiology of glucose metabolic abnormalities is poorly understood, but insulin insufficiency is clearly the main component. Findings from animal studies have provided insight into the pathophysiology of CFRD, and imply that carbohydrate metabolic abnormalities might begin at much younger ages than was previously thought in patients with cystic fibrosis, and might be related to the basic cystic fibrosis chloride channel defect. In this Review we explore present knowledge of CFRD in children and adolescents, and new data that indicate that the pathophysiology of CFRD begins in very young patients.

Diabetes in cystic fibrosis

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.

Update on cystic fibrosis-related diabetes

Diabetes mellitus has emerged as a common comorbidity in cystic fibrosis and is considered a clinical entity (cystic fibrosis-related diabetes, CFRD) distinct from that of type 1 diabetes (T1DM) and type 2 diabetes (T2DM). The relevance of this diagnosis extends not only from its imposition of additional medical burden but its association with worse health outcomes in individuals with CF. 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.

Targeting the Intracellular Environment in Cystic Fibrosis: Restoring Autophagy as a Novel Strategy to Circumvent the CFTR Defect

Cystic fibrosis (CF) patients harboring the most common deletion mutation of the CF transmembrane conductance regulator (CFTR), F508del, are poor responders to potentiators of CFTR channel activity which can be used to treat a small subset of CF patients who genetically carry plasma membrane (PM)-resident CFTR mutants. The misfolded F508del-CFTR protein is unstable in the PM even if rescued by pharmacological agents that prevent its intracellular retention and degradation. CF is a conformational disease in which defective CFTR induces an impressive derangement of general proteostasis resulting from disabled autophagy. In this review, we discuss how rescuing Beclin 1 (BECN1), a major player of autophagosome formation, either by means of direct gene transfer or indirectly by administration of proteostasis regulators, could stabilize F508del-CFTR at the PM. We focus on the relationship between the improvement of peripheral proteostasis and CFTR PM stability in F508del-CFTR homozygous bronchial epithelia or mouse lungs. Moreover, this article reviews recent pre-clinical evidence indicating that targeting the intracellular environment surrounding the misfolded mutant CFTR instead of protein itself could constitute an attractive therapeutic option to sensitize patients carrying the F508del-CFTR mutation to the beneficial action of CFTR potentiators on lung inflammation.