Effect of nifedipine on glucose tolerance, serum insulin, and serum fructosamine in diabetic and nondiabetic patients.

The hypothesis that nifedipine may cause an insidious but reversible change in glucose tolerance, similar to that associated with thiazide therapy, was studied in six nondiabetic and six noninsulin-dependent diabetic patients with hypertension. After medium-term nifedipine therapy (mean duration, 11.5 months) was stopped for one month and then resumed for a month, values for fasting blood glucose, fasting serum insulin, serum fructosamine, glucose tolerance, and insulin release in response to oral glucose were unchanged in both groups. These findings suggest that nifedipine in conventional doses does not have important effects on glucose handling in either diabetic or nondiabetic patients.