The influence of Verapamil, a calcium antagonist, on circulating levels of glucose, insulin and glucagon has been evaluated in 5 normal subjects and in 5 patients with non insulin-dependent diabetes (NIDDM). An oral glucose tolerance test was performed both in basal conditions and during intravenous infusion of the drug (5 mg/h). Administration of Verapamil didn't induce any significant change on the three parameters. The small decrease of glycemia in patients affected by NIDDM and treated with Verapamil was not related to reduction of glucagonemia.