Lack of Effect of Nicardipine and Diltiazem on Glucose- and Arginine-induced Insulin Release in Obese Subjects

The metabolic effects of calcium channels blockers have already been studied both in normal and diabetic humans and results were quite controversial, depending on the drug used, the dose administered, and the type of patient. Little information exists on the use of Ca2+ antagonists in obese people, even if these persons are a population risk group for developing diseases in which these drugs may be requested for treatment. Thus, we evaluated, in obese humans, the metabolic effects of two Ca2+ antagonist drugs recently made commercially available to treat diseases such as hypertension and ischemic heart disease: nicardipine and diltiazem. Sixteen obese subjects were submitted to an intravenous glucose tolerance test (0.33 g/kg) (IVGTT) and an arginine test tolerance (30 g in 30 minutes) (ATT) before and after a week of oral treatment with nicardipine (60 mg/day) or diltiazem (360 mg/day). Plasma values of glucose, insulin, and C-peptide during IVGTT, and of glucose, insulin and glucagon during ATT did not show any modification during treatment with either drug. Thus the Ca2+ antagonists, nicardipine and diltiazem, at therapeutic doses in obese subjects do not significantly affect glucose tolerance or insulin and glucagon release.