Insulin sensitivity in newly detected hypertensive patients: influence of captopril and other antihypertensive agents on insulin sensitivity and related biological parameters

Abstract

In a recent study in which metabolic characteristics of newly detected obese and nonobese hypertensive subjects were compared with those of normotensive subjects, insulin sensitivity was decreased, fasting insulin values and insulin values after an intravenous glucose tolerance test (IVGTT) were increased, and fasting and IVGTT glucose values were increased in both hypertensive groups. Furthermore, adverse alterations in lipid profile variables were found in the hypertensive groups when compared with the normotensive group. The effects of various antihypertensive agents on these metabolic variables have been assessed in prospective trials. Treatment with the beta 1-selective blocking agents metoprolol and atenolol was associated with decreased insulin sensitivity and increased fasting values of insulin and glucose. There were also indications of a suppressive effect on insulin secretion during IVGTT, as well as an increase in serum triglycerides and a decrease in serum high-density lipoprotein cholesterol. Hydrochlorothiazide treatment was associated with a decrease in insulin sensitivity and an increase in blood glucose concentrations. In addition, hydrochlorothiazide increased total cholesterol, particularly the low-density lipoprotein fraction. The calcium channel blocker diltiazem did not appear to produce any negative metabolic effects. Treatment with the angiotensin converting enzyme inhibitor captopril resulted in increased insulin sensitivity with no adverse effects on lipids. All of the agents reduced blood pressure to a similar degree. These findings, and those of other studies, suggest that captopril and diltiazem offer advantages over the other agents with regard to effects on risk factors for coronary artery disease other than hypertension. Unlike diltiazem, captopril improves insulin sensitivity and this may prove to be important.