α‐Glucosidase inhibition (acarbose) fails to enhance secretion of glucagon‐like peptide 1 (7–36 amide) and to delay gastric emptying in Type 2 diabetic patients

Aim  Acarbose is able to enhance GLP-1 release and delay gastric emptying in normal subjects. The effect of α-glucosidase inhibition on GLP-1 has been less evident in Type 2 diabetic patients. The aim of this study was to investigate the possible influence of acarbose on GLP-1 release and gastric emptying in Type 2 diabetic patients after a mixed test meal. Patients and methods  Ten Type 2 diabetic patients were tested with 100 mg acarbose or placebo served with a mixed meal that was labelled with 100 mg 13C-octanoic acid. Plasma concentrations of glucose, insulin, C-peptide, glucagon, GLP-1 and GIP were determined over 6 h. Gastric emptying was measured by determining breath 13CO2 using infrared absorptiometry. Statistics  repeated-measures anova. Results  Gastric emptying rates (t1/2: 162 ± 45 vs. 163 ± 62 min, P = 0.65) and plasma concentrations (increasing from ≈ 12 to ≈ 25 pmol/l, P = 0.37) and integrated responses of GLP-1 (P = 0.37) were not changed significantly by acarbose treatment. Postprandial plasma glucose concentrations (P < 0.0001) and their integrated responses were lowered by acarbose (by 64%; P = 0.016). The plasma concentrations of insulin and C-peptide were reduced (P = 0.007 and 0.057, respectively) by acarbose, while glucagon was not changed (P = 0.96). GIP plasma concentrations (increasing with placebo from ≈ 10 to ≈ 85 pmol/l and with acarbose to ≈ 55 pmol/l (P < 0.0001) and their integrated responses were significantly lowered (by 43%) by acarbose (P = 0.021). After 2 weeks of acarbose treatment (50 mg t.i.d. for the first and 100 mg t.i.d. for the second week, n = 6), similar results were found. Conclusions  In hyperglycaemic Type 2 diabetic patients, ingestion of acarbose with a mixed test meal failed to enhance GLP-1 release and did not influence gastric emptying.