Effects of nifedipine and nitrendipine on insulin secretion in obese patients

Data on the influence of calcium antagonists on glucose tolerance and insulin release in humans are conflicting. The present double-blind, double-dummy, controlled trial was designed to investigate the effect of a short-term (7 days) treatment with nitrendipine, 20 mg b.i.d.; nitrendipine, 20 mg once daily; or placebo on blood glucose and plasma insulin and C-peptide response to an intravenous glucose load in mildly or transiently hypertensive nondiabetic obese patients. No statistically significant differences were found in fasting glucose, insulin, and C-peptide, or in the glucose disappearance rate and in any of the parameters for insulin and C-peptide response after i.v. glucose, between the three groups of patients. However, a slight decrease in early insulin response to glucose was observed in the nifedipine and the nitrendipine groups. This study confirms that calcium antagonists have no clinically relevant effect on glucose homeostasis even if a slight alteration of insulin release after glucose load cannot be ruled out.