Metabolic syndrome and risk for Type 2 diabetes.

The phenomenon of risk factor clustering is known as metabolic syndrome. Metabolic syndrome is an aggregation of metabolic risk factors for cardiovascular disease and Type 2 diabetes. Risk factor clustering occurs in individuals, but its specific cause(s) remain incompletely known. Insulin resistance and central obesity are involved in many cases. There are five current definitions of metabolic syndrome, but they do not identify equivalent phenotypes, and the most widely promoted definition, Adult Treatment Panel 3 metabolic syndrome, is not uniformly associated with insulin resistance. Metabolic syndrome appears to increase risk for subsequent Type 2 diabetes by three- to over 30-fold compared with no metabolic syndrome, but metabolic syndrome in the absence of insulin resistance may not be a diabetes risk factor. Metabolic syndrome can discriminate subjects at risk of diabetes, but diabetes prediction models provide more precise estimates of future risk. Whether metabolic syndrome is easier to use than other strategies to identify diabetes risk remains to be demonstrated. Given an uncertain pathophysiologic foundation and ongoing confusion about definitions, it is premature to recommend specific drug therapy for metabolic syndrome. Elevated levels of its component traits should be treated individually according to evidence-based guidelines. Therapeutic lifestyle change is the only proven treatment for metabolic syndrome to reduce its prevalence or prevent the onset of diabetes.