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 alpha-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 C-13-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 (CO2)-C-13 using infrared absorptiometry. Statistics repeated-measures ANOVA. Results Gastric emptying rates (t(1/2): 162 +/- 45 vs. 163 +/- 62 min, P = 0.65) and plasma concentrations (increasing from approximate to 12 to approximate 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 approximate to 10 to approximate to 85 pmol/l and with acarbose to approximate 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.