EFFECTS OF NITRENDIPINE ON GLUCOSE-TOLERANCE AND SERUM-INSULIN AND DEHYDROEPIANDROSTERONE SULFATE LEVELS IN INSULIN-RESISTANT OBESE AND HYPERTENSIVE MEN

To determine whether the calcium channel blocker nitrendipine improves glucose tolerance, lowers circulating insulin, and raises serum dehydroepiandrosterone sulfate (DHEA-8) levels in insulin-resistant men, a total of 15 obese and hypertensive men were enrolled in a single blind, placebo-controlled study. A nitrendipine group (n = 8) and a placebo group (n = 7) were studied before and after treatment with either nitrendipine (10 mg) or a placebo capsule, twice daily for 7 days, by determining serum insulin, glucose, and DHEA-S levels in the fasting state and during an oral glucose tolerance test. Nitrendipine treatment 1) lowered fasting serum insulin from 265 +/- 24 to 194 +/- 22 pmol/L (P < 0.01) without changing fasting serum glucose, 2) reduced both the area under the curve for glucose (from 1246 +/- 31 to 1091 +/- 26 mmol/L . min; P < 0.005) and the area under the curve for insulin (from 123.6 +/- 9.4 to 82.9 +/- 10.0 nmol/L . min; P < 0.015) during the oral glucose tolerance test, and 3) increased fasting serum DHEA-S by 63% from 4.21 +/- 0.17 to 6.84 +/- 0.21 mumol/L (P = 0.0001). No change was noted in the placebo group. We conclude that nitrendipine treatment is associated with improved glucose tolerance, reduced fasting and glucose-stimulated serum insulin levels, and increased circulating DHEA-S levels.