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 Ca 2+ 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 Ca ~+ 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) (IVGTr) and an arginine test tolerance (30 g in 30 minutes) (ATY) before and after a week of oral treatment with nicardipine (60 rag/day) or diltiazem (360 rag/day). Plasma values of glucose, insulin, and C-peptide during IVGTT, and of glucose, insulin and glucagon during ATY did not show any modification during treatment with either drug. Thus the Ca z+ antagonists, nicardipine and diltiazem, at therapeutic doses in obese subjects do not significantly affect glucose tolerance or insulin and glucagon release.