The ethanol augmentation of glucose-induced insulin secretion is abolished by calcium antagonism with nifedipine: no evidence for a role of glucagon-like peptide-1 (GLP-1).

We studied the effect of ethanol and calcium antagonism (nifedipine) on insulin- (n = 8) and glucagon-like peptide-1 (GLP-1) (n = 6) secretion in healthy subjects. Four experiments in random order were performed (control, ethanol, nifedipine, and combination). Intravenous glucose tolerance tests were performed with and without pretreatment with oral ethanol and nifedipine. Ethanol pretreatment was followed by increased insulin (ethanol vs. control; p < 0.01) and C-peptide (ethanol vs. control; p < 0.05) areas after intravenous glucose (0-20 min), indicating that ethanol augments insulin secretion. Calcium antagonism with nifedipine abolished the ethanol augmentation of insulin secretion (insulin area 0-20 min, ethanol vs. combination, p < 0.05; and C-peptide area 0-20 min, ethanol vs. combination, p < 0.01). The GLP-1 response (area 0-90 min) was not significantly affected by ethanol.