The effect of enalapril with and without hydrochlorothiazide on insulin sensitivity and other metabolic abnormalities of hypertensive patients with NIDDM

The effect of 20 mg of enalapril with and without 12.5 mg of hydrochlorothiazide on glucose metabolism insulin sensitivity and lipids was evaluated in hypertensive non-insulin-dependent diabetes. Ten mild to moderate hypertensive patients with non-insulin-dependent diabetes mellitus were treated for 8 weeks with 20 mg enalapril once a day, and then divided into two groups of 5 patients each for a second 8 weeks of treatment with enalapril alone or in combination with hydrochlorothiazide, 12.5 mg once a day. Blood pressure, fasting plasma glucose, lipids and insulin, glycosylated hemoglobin, and insulin sensitivity were measured at baseline and after 8 and 16 weeks. Results were analyzed by the ANOVA test for repeated measures and all values are given as mean ± SD. Diastolic blood pressure decreased significantly after the first and second period of enalapril and after the combination of enalapril and hydrochlorothiazide. Glycosylated hemoglobin dropped significantly after the first and second period of enalapril monotherapy. Plasma triglycerides and fasting plasma insulin decreased significantly after the 16 weeks of enalapril. Insulin-mediated glucose uptake increased significantly after 8 and 16 weeks of monotherapy with enalapril. No significant difference was observed in any of the metabolic characteristics, including insulin sensitivity, between the values after 8 weeks of enalapril alone and the final values of the enalapril-treated and the enalapril/hydrochlorothiazide-treated groups. It is concluded that enalapril improves some of the metabolic parameters, including insulin sensitivity, of hypertensive diabetic patients. Despite the small number of hydrochlorothiazide patients, these results lead us to suggest that the coadministration of low-dose hydrochlorothiazide may not adversely affect these parameters, and that enalapril may have blunted the metabolic adverse effect of the diuretic.