Diabetogenic effect of nifedipine.

This case report describes a 60-year-old diabetic patient whose daily insulin requirements increased by 30 percent following nifedipine administration. Glucagon and intravenous glucose tolerance tests were performed with and without nifedipine treatment, in order to evaluate the roles of decreased pancreatic beta islet cell function and augmented insulin peripheral resistance in the diabetogenic effect of nifedipine. Insulin and calculated glucose peripheral utilization extrapolated from the glucose concentration curves were not significantly different. C-peptide levels tended to be lower with nifedipine treatment at baseline and during the glucagon tests. This may suggest that the altered glycemic control associated with nifedipine was mediated by a suppressed islet beta cell function. The effect of calcium channel-blockers upon glycemic control and the possible mechanisms involved are discussed.