Is treatment of insulin resistance beneficial independent of glycemia?

The clinical definition of the Insulin Resistance or Metabolic Syndrome is shown in Table 1. Subjects who fulfill these criteria are at increased risk for cardiovascular disease (CVD). The criteria of the National Cholesterol Education Program are more clinically relevant because those measurements are readily available. Although those with impaired fasting glucose and/or impaired glucose tolerance (IGT) are at increased risk for the subsequent development of type 2 diabetes (3), abnormal glycemia is not an independent predictor of cardiovascular disease once the other risk factors are taken into account (4,5). Three recent randomized, controlled studies have shown that lifestyle intervention with diet and exercise can decrease the development of type 2 diabetes in subjects with IGT (6–8). However, although exercise is associated with less CVD (9), the hypothesis that exercise decreases CVD has never been directly tested in a randomized, controlled clinical trial. Insulin resistance, highly associated with visceral fat accumulation (10), characterizes the Insulin Resistance or Metabolic Syndrome. Furthermore, measured insulin resistance predicts CVD (11). In this issue of Diabetes Care , Shadid and Jenson (12) compare the effects of diet and exercise versus pioglitazone in insulin-resistant nondiabetic men and premenopausal women with upper body obesity (i.e. visceral fat accumulation). Insulin sensitivity increased in both groups. Those given diet and exercise showed weight loss and decreased visceral, subcutaneous, total body, and leg fat, whereas the subjects prescribed …