Present study was carried out in order to control if glucose tolerance and insulin secretion changed during nicardipine treatment in healthy or in non-insulin dependent diabetics. In the 8th day of therapy with nicardipine (40 mg/day), glucose tolerance and insulin secretion were unmodified in a group of 20 non-diabetic patients. At the same time glucose tolerance was found improved in the group of 14 non-insulin dependent diabetic without a contemporary variation of insulin secretion. Such a result, note-worthy for a drug frequently administered to diabetics, could be due to inhibited glucagon secretion, or to increased glucose uptake by hepatocytes.