Ten male patients, recovered from acute myocardial infarction, and ten control subjects were investigated by a 50 g glucose tolerance test. All patients and control subjects had normal glucose tolerance, but the patients had increased fasting and integrated insulin response to oral glucose. Fasting gastric inhibitory polypeptide concentrations and integrated gastric inhibitory polypeptide response were normal in the patients. The exaggerated insulin secretion in patients recovered from myocardial infarction does not seem to be caused by increased secretion of gastric inhibitory polypeptide.