The subjects, 15 noninsulin-dependent diabetic hypertensive patients (mean age, 61 years) and 15 nondiabetic hypertensive patients (mean age, 60 years), received placebo for four weeks and then 20 to 40 mg of nitrendipine once daily for 24 weeks. At the end of the placebo period their blood pressures were greater than or equal to 160 mmHg systolic or greater than or equal to 95 mmHg diastolic. Blood pressures declined significantly during treatment in both patient groups; after 24 weeks, 13 of 15 diabetic patients and 12 of 15 nondiabetic patients were normotensive (diastolic blood pressure less than 90 mmHg). Meanwhile, heart rate, indices of glycemic control (serum glucose, hemoglobin A1c, fructosamine, and C-peptide levels), and serum lipids (cholesterol, high-density cholesterol, triglycerides, apolipoprotein A1 and B levels) did not change. It is concluded that nitrendipine does not impair glucose or lipid metabolism in diabetic hypertensive patients.