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.

Gastric Emptying Is More Rapid in Adolescents With Type 1 Diabetes and Impacts on Postprandial Glycemia

CONTEXT

Gastric emptying is a critical determinant of postprandial glycemic control in health and type 1 diabetes. There are few studies that assess the relationship between gastric emptying and postprandial glycaemia in adolescents with type 1 diabetes.

OBJECTIVE

The objectives of the study were to quantify gastric emptying in adolescents with type 1 diabetes and examine its relationship to postprandial glycaemia and autonomic function.

DESIGN

This was a case-control study. Gastric half-emptying time of a solid meal was measured by a (13)C-octanoate breath test. Cardio-autonomic function was measured by heart rate variability. Chronic and postprandial gastrointestinal symptoms were evaluated by questionnaire and visual analog scales. Blood glucose concentrations were monitored frequently during the study.

SETTING

The study was conducted at a tertiary pediatric hospital in South Australia.

PARTICIPANTS

Thirty adolescents (aged 15 ± 2.5 y) with type 1 diabetes and age- and sex-matched controls (gastric emptying, n = 20; heart rate variability, n = 135) participated in the study.

MAIN OUTCOME

Gastric half-emptying time was the main outcome in the study.

RESULTS

Gastric emptying was more rapid in subjects with type 1 diabetes than controls [median half emptying time 78 (interquartile range 61-99) vs 109 (interquartile range 71-124) min, P = .02]. The postprandial rise in blood glucose at 60 minutes was strongly related to gastric half-emptying time (R = -0.65, P = .0001). Gastric emptying was slower in subjects with fasting hyperglycemia but was not related to heart rate variability. Nausea, bloating, and anxiety were related to fasting glycemia (P = .03).

CONCLUSION

Rapid gastric emptying is a major determinant of postprandial glycemia in adolescents with type 1 diabetes. This observation has significant implications for therapy.

Pancreatic enzyme supplementation improves the incretin hormone response and attenuates postprandial glycemia in adolescents with cystic fibrosis: a randomized crossover trial

CONTEXT

Cystic fibrosis-related diabetes is characterized by postprandial, rather than fasting, hyperglycemia. Gastric emptying and the release of the incretin hormones [glucagon-like peptide-1 (GLP-1) and glucose dependent insulinotropic polypeptide (GIP)] are central to postprandial glycemic control. Lipolysis is required for fat to slow gastric emptying and stimulate incretin release.

OBJECTIVE

We aimed to determine the effect of pancreatic enzyme replacement therapy (PERT) on postprandial glycemia in adolescents with cystic fibrosis (CF).

DESIGN

This was a double-blinded randomized crossover trial. Subjects consumed a high-fat pancake, with either PERT (50 000 IU lipase) or placebo. Gastric emptying was measured by a breath test and blood sampled frequently for plasma blood glucose, insulin, glucagon, GLP-1, and GIP. Data were also compared with seven healthy subjects.

PARTICIPANTS

Fourteen adolescents (13.1 ± 2.7 y) with pancreatic-insufficient CF and seven healthy age-matched controls participated in the study.

MAIN OUTCOME MEASURE

Postprandial hyperglycemia was measured as peak glucose and area under the curve for blood glucose at 240 minutes.

RESULTS

CF subjects had postprandial hyperglycemia compared with controls (area under the curve, P < .0001). PERT reduced postprandial hyperglycemia (P = .0002), slowed gastric emptying (P = .003), and normalized GLP-1 and GIP secretion (P < .001 for each) when compared with placebo, without affecting insulin.

CONCLUSION

In young people with pancreatic insufficient CF, PERT markedly attenuates postprandial hyperglycemia by slowing gastric emptying and augmenting incretin hormone secretion.