Effects of nifedipine on insulin secretion and glucose metabolism in rats and in hypertensive type 2 (non-insulin dependent) diabetics.

The effects of nifedipine (Adalat) on glucose metabolism and insulin release were studied in rats and in patients with type 2 diabetes mellitus complicated with hypertension. 1. In rats, 2.5-50 micrograms/kg of intravenous nifedipine reduced glucose tolerance and insulin release after intravenous glucose in a dose related fashion, although fasting blood sugar and insulin were not affected at 50 micrograms/kg of nifedipine. 2. Daily 20 to 60 mg of oral nifedipine for 12-75 weeks to 14 type 2 diabetics with hypertension did not affect their fasting blood glucose or hemoglobin A1. Mean glucose tolerance curve after the treatment was significantly ameliorated, although insulin response during the oral glucose loading did not show any significant change. Those results suggest firstly that there may be a difference in insulinopenic effect of nifedipine between the species, and secondly that long-term administration of nifedipine produced no adverse influence on glucose metabolism in type 2 diabetics.