Effect of nifedipine on glucose potentiation of the acute insulin response to arginine in non-insulin-dependent diabetics.

The effect of 7-days of nifedipine treatment on insulin secretion has been analyzed in hypertensive patients with non-insulin-dependent mellitus (NIDDM). Pancreatic beta-cell function was assessed as insulin release following stimulation with arginine after potentiation by hyperglycaemia. Two groups of 5 patients with NIDDM (fasting blood glucose 139.2 mg.dl-1), on the same controlled diet, were compared; one was treated with nifedipine 30 mg per d and the other was the control. The mean blood pressure in the nifedipine group decreased (110 vs 102 mm Hg). Fasting blood glucose and basal plasma insulin were not affected by nifedipine. The acute insulin response (AIR) to 5 g arginine after potentiation by hyperglycaemia (clamped at 240 and 350 mg/dl for 30 min) was significantly (P less than 0.05) decreased, as well as the potentiation slope (line relating AIR and plasma glucose level) in those patients, and were unchanged in the control group. Thus, nifedipine may impair insulin secretion at high glucose levels in patients with NiDDM.