Abstract

BACKGROUND
Angiotensin converting enzyme (ACE) inhibitors are becoming increasingly popular as the first-choice antihypertensive agents for diabetic patients. This could be partly related to their suggested beneficial effects on insulin sensitivity. This study was designed to compare the effect of captopril with that of control (nitrendipine) on insulin sensitivity for subjects with insulin resistance. METHODS: 24 subjects, aged less than 60 years, with their insulin resistance being defined as the area under the curve (AUCi) of insulin that was 2 standard deviations (SD) more than that of the control subjects during oral glucose tolerance test were recruited. A randomized, double-blind, crossover trial was conducted for an 8 weeks treatment period with captopril and the control (nitrendipine) that was given after an initial 6 weeks run-in period. Anthropometric measurement including weight, height, waist and hip circumference, blood pressure (systolic & diastolic), lipid profile blood chemistry, electrolytes levels & renal function testing, and frequently sampled intravenous glucose tolerance tests (FSIGT) for the insulin sensitivity index (SI) & acute insulin response to glucose (AIRg) were also done before and after treatment, respectively. RESULTS: 18 subjects (6 males, 12 females) completed the study. The mean age of the study subjects was 47.9+/-2.9 years (mean+/-SEM), and their BMI was 28.0+/-0.7 kg/m2 (mean+/-SEM).There was a significant decrease in weight (baseline; 71.5+/-9.2 kg vs. captopril; 70.7+/-9.0 kg and nitrendipine; 709+/-9.2 kg, p<0.05, respectively) and BMI (baseline; 28.0+/-3.0 kg/m2 vs. captopril; 27.7+/-2.8 kg/m2 and nitrendipine; 27.8+/-2.9 kg/m2, p<0.05, respectively) for both groups compared with the baseline, but there are no significant differences between the two groups. Triglyceride was significantly decreased after treatment with captopril compared to the baseline and nitrendipine (187.0+/-99.5 mg/dL vs. 224.5+/-134.2 mg/dL, respectively, p<0.05). The SI was significantly increased after captopril treatment compared with the baseline (1.4+/-1.0 vs. 2.5+/-0.8 min-1 per mU/ml, respectively, p<0.05), and the captopril group was significantly higher than that of nitrendipine (1.5+/-1.0 min-1 per mU/ml, p <0.05). Acute insulin response to glucose in both groups was also increased after treatment, but there was no statistically significance. CONCLUSION: Captopril therapy improved insulin sensitivity, and it decreased the concentration of fasting insulin in subjects with insulin resistance.

• Keywords: Captopril;Angiotensin converting enzyme inhibitors;Insulin resistance;Insulin sensitivity;Insulin;