Metabolic risk varies in obese individuals.(CLINICAL ROUNDS)

Metabolic risk factors can vary widely among similarly obese individuals, which suggests that obesity is merely one of the factors contributing to insulin resistance and cardiovascular disease, according to the findings of an observational study.

"Insulin action is influenced by many factors, and overweight/obesity is only one of them. Otherwise, all overweight people would be very insulin-resistant and all thin people would be insulin-sensitive," Dr. Gerald M. Reaven said at the Sixth World Congress on the Insulin Resistance Syndrome.

Dr. Reaven, professor of medicine at Stanford (Calif.) University, and his associates, compared cardiovascular risk factors in 211 obese individuals (body mass index 30-35 kg/[m.sup.2]) who were divided into three groups according to their degree of insulin resistance. Group one was the most insulin sensitive, group two was intermediate, and group three was the most insulin resistant.

Only 1% of the individuals in group one had impaired glucose tolerance as measured by their steady-state plasma glucose, compared with 46% of the individuals in group three.

Overall, a third of the study cohort had a lower estimated risk of developing cardiovascular disease based on their lipid, plasma glucose, and blood pressure levels as well as other parameters of the metabolic syndrome, compared with the other two-thirds of the cohort.

These findings suggest that "not all obese people are created equal, meta-bolically speaking. Even within the obesity, something else is going on. We need to find out what that is," Dr. Reaven said in an interview.

"Insulin-mediated glucose disposal varies more than sixfold in apparently healthy individuals. Only about 25% of this variability is related to differences in body weight. Although people who are overweight or obese tend ...