[Changes in insulin sensitivity after weight loss in hypertensive patients with obesity]

To assess the role of insulin resistance in the hypotensive effect of weight loss, insulin sensitivity was examined by the euglycemic insulin clamp method in 15 untreated obese hypertensive patients with a body mass index of 25 kg/m2 or greater (4 men and 11 women, with a mean age of 53.4 years) before and 4 weeks after being placed on a low-calorie diet of 800 Cal/day with mild exercise. Body weight decreased by 11.0% (from 74.3 +/- 3.8 to 66.1 +/- 3.0 kg; p < 0.01) with a concomitant fall of mean blood pressure from 122.5 +/- 2.3 to 108.6 +/- 2.4 mmHg (p < 0.01). Glucose infusion rate (GIR), as an index of insulin sensitivity, was significantly increased by 54.3% (from 3.66 +/- 2.4 to 5.5 +/- 9.3 ml/kg/min; p < 0.01). Plasma levels of fasting blood sugar and insulin decreased significantly by 11.8% and 58.4%, respectively (both p < 0.01). The change in mean blood pressure showed a negative correlation with the change in GIR resulting from weight loss (r = -0.79, p < 0.05). These findings suggest that the hypotensive effect of weight loss in hypertensive patients with obesity is partly related to improvement of insulin sensitivity.