Effects of nitrendipine on plasma levels of insulin and glucose in patients with essential hypertension

In this randomized, double-masked, parallel-group study we assessed the effects of the calcium-channel blocker nitrendipine (10 or 20 mg) and placebo on blood pressure, glucose tolerance, and plasma insulin and cholesterol levels in 24 patients (17 men and 7 women; mean age, 44 ± 6 years) with mild-to-moderate essential hypertension. The basal insulin plasma level and the level after administration of an oral glucose load of 75 g were determined before and after the 16-week study. Patients in the nitrendipine group showed a significant decrease in sitting and standing blood pressures (from 165 ± 9.6/103 ± 6 mm Hg to 144 ± 19/91 ± 7 mm Hg and from 163 ± 7/103 ± 4 mm Hg to 144 ± 15/95 ± 7 mm Hg, respectively). Plasma glucose concentration in the nitrendipine group decreased significantly at 90 (140 ± 13 vs 183 ± 9 mg/dL, P < 0.05, before and after treatment, respectively) and 120 (121 ± 1 vs 105 ± 8 mg/dL, P < 0.01 before and after treatment, respectively) minutes after administration of the oral glucose load. Moreover, after 16 weeks (12 weeks of treatment), the nitrendipine group showed significantly reduced plasma insulin levels (68 ± 13 vs 48 ± 10 μU/mL, P < 0.05, before and after treatment, respectively) during the oral glucose tolerance test, while plasma cholesterol levels (188 ± 7 vs 184 ± 6 mg/dL, not significant, before and after treatment, respectively) did not change significantly. This study indicates that the antihypertensive effect of nitrendipine is associated with the favorable metabolic effects of improved insulin sensitivity and glucose tolerance.