Effect of angiotensin-converting enzyme inhibition on endothelial function and insulin sensitivity in hypertensive patients

Introduction Evidence suggests an association between insulin resistance, hypertension and impaired endothelial function. Studies have shown that insulin resistance precedes the development of hypertension. By improving insulin sensitivity, it may be possible to improve hypertension and the subsequent damage to vessel walls. Some data indicates beneficial effects of angiotensin-converting enzyme (ACE) inhibitors on insulin sensitivity and endothelial function. We aimed to investigate these effects of ACE inhibition in the same group of patients with essential hypertension. Materials and methods Nine non-smoking, untreated hypertensive patients (38.3 9 years, 4/5 male/female) and 12 age-matched healthy subjects (35.2 6.7 years, 5/7 male/female) were included in the study. Hypertensive patients were given enalapril maleate (5—40 mg/day) for six months. The following parameters were studied at baseline and at the end of treatment period. Whole body insulin sensitivity was measured by a formula derived from an oral glucose tolerance test and named I as the insulin sensitivity index (ISI). Insulin was measured by chemiluminescence and glucose by a glucose oxidase method. Endothelial function was evaluated as flow-mediated dilatation (FMD) of the brachial artery by ultrasonography and expressed as a percentage change relative to baseline diameter. Endothelialindependent vasodilatation was measured after sublingual nitroglycerine. Results FMD was impaired in the hypertensive group compared with healthy subjects (7.3 3.1% vs. 15.3 4.8%, p