The metabolic syndrome: practical guide to origins and treatment: Part I.

The metabolic syndrome (MetS), a cluster of metabolic abnormalities with insulin resistance as a major characteristic, has gone by several names over the past two decades. The diagnostic criteria proposed by the Adult Treatment Program III (ATP III) of the National Cholesterol Education Program (NCEP) have led to greater awareness of the components and treatment strategies.1 Five diagnostic traits are listed in the ATP III version of the MetS (Table; referred to as the “metabolic syndrome”), and the presence of any 3 of these factors is considered sufficient for diagnosis. This practical review will consider each in turn, providing advice for cardiologists, internists, and other health care providers who are diagnosing and treating persons with the syndrome in an effort to prevent a variety of clinical outcomes. The major adverse consequence of the MetS is cardiovascular disease (CVD). Several of the metabolic abnormalities associated with the syndrome, in fact, are CVD risk factors. One of these abnormalities, insulin resistance, also predisposes to the development of type 2 diabetes mellitus (T2DM). In age-adjusted estimates from the National Health and Nutrition Examination Survey III in 1998 to 1994, approximately 24% of adult Americans had 3 of the 5 MetS criteria. Key determinants of greater prevalence were age and ethnicity. Prevalence rates were highest in Mexican Americans and were successively lower in white, African American and other racial groups.2 These published estimates included persons with diabetes mellitus who had met the 1998 fasting glucose criteria ( 126 mg/dL [8.0 mmol/L]) of the American Diabetes Association.3 This article will focus on the features of the MetS in persons without diabetes mellitus, although most persons with T2DM also have the MetS. Moreover, the therapeutic approaches to metabolic risk factors described here also can be applied to most patients with T2DM.