Cardiovascular risk in the metabolic syndrome: fact or fiction?

In population-based studies, a cluster of cardiovascular risk factors comprising the metabolic syndrome (MetS) has been documented as predictive of cardiovascular disease events and type 2 diabetes. Currently, there are several proposed definitions of the MetS, although data support some advantages of using the 2005 National Cholesterol Education Program Adult Treatment Panel III definition, which is considered superior to most others, including the one from the 2005 International Diabetes Federation study. One controversial issue is that some of the conventional cardiovascular risk factors included in the MetS cluster appear to be equally predictive of cardiovascular outcomes as the syndrome itself (eg, the influence of smoking habits). Further observational and intervention studies are needed to explore this issue and target the core problem of the syndrome, which is proposed to be insulin resistance. Useful therapies for the metabolic syndrome include lifestyle modification and drugs that lower conventional cardiovascular risk factors, such as metformin, the "glitazones," and evidence-based drugs.