Relations Between Fasting Serum Insulin, Glucose, and Dihydroepiandrosterone-Sulfate Concentrations in Obese Patients with Hypertension: Short-Term Effects of Antihypertensive Drugs

A randomized, single-blind, placebo-controlled study was conducted in 82 obese patients with mild to moderate essential hypertension, to determine the incidence of hyperinsulinemia, the relations between fasting insulin and dihydroepiandrosterone-sulfate (DHEA-S) levels, and the short-term effects of antihypertensives on DHEA-S and insulin serum concentrations. Increased insulin/glucose ratios (IGR) suggestive of insulin resistance were found in half of our patients. Hyperinsulinemic and normoinsulinemic obese patients with hypertension had comparable fasting glucose and DHEA-S concentrations and comparable blood pressure (BP) levels. Thus no relations were found between fasting insulin and DHEA-S levels. Fasting hyperinsulinemia was found in only half of the obese subjects with hypertension, suggesting that not all obese patients with hypertension are at the same high cardiovascular risk. Short-term treatment with captopril, prazosin, verapamil, atenolol, or hydrochlorothiazide (HCTZ) reduced BP; greater BP reduction was observed with drugs with vasodilatory effects. Captopril, prazosin, and verapamil reduced fasting insulin levels, whereas atenolol and hydrochlorothiazide did not. The former drugs reduced fasting insulin levels that were either within normal limits or in the hyperinsulinemic range. None of the drug treatments produced significant increases in serum DHEA-S concentrations, although some of them considerably reduced fasting insulin levels. No relations between insulin and DHEA-S levels were observed either at baseline or at the end of the antihypertensive treatment. The BP reduction resulting from the peripheral vasodilation may explain the insulin-reducing action of captopril, verapamil, and prazosin. These results further emphasize the large heterogeneity present in the pathophysiologic mechanisms operating in obesity and hypertension.