Clinical Management of Metabolic Syndrome: Report of the American Heart Association/National Heart, Lung, and Blood Institute/American Diabetes Association Conference on Scientific Issues Related to Management

"The National Cholesterol Education Program’s Adult Treatment Panel III report (ATP III)1 identified the metabolic syndrome as a multiplex risk factor for cardiovascular disease (CVD) that is deserving of more clinical attention. Subsequently, the National Heart, Lung, and Blood Institute (NHLBI), in collaboration with the American Heart Association (AHA), convened a conference to examine scientific issues related to definition of the metabolic syndrome.2 The present report summarizes a second conference devoted to clinical management of the metabolic syndrome, which was sponsored by the AHA in partnership with the NHLBI and cosponsored by the American Diabetes Association (ADA). This latter conference considered the following issues: (1) pathogenesis and presentation of the metabolic syndrome, (2) management of underlying risk factors, (3) management of metabolic risk factors, and (4) unresolved issues and research challenges. The conference on definition2 confirmed CVD as a major clinical outcome of metabolic syndrome and identified 6 major components of the syndrome: abdominal obesity, atherogenic dyslipidemia, elevated blood pressure, insulin resistance ± glucose intolerance, a proinflammatory state, and a prothrombotic state. The follow-up conference on management was structured around therapies for these components. Clinical recognition of the metabolic syndrome is generally based on finding several well-recognized signs in clinical practice: abdominal obesity, elevated triglycerides, reduced HDL cholesterol, raised blood pressure, and elevated plasma glucose. In addition, research shows that other components not routinely measured commonly aggregate with the major components: elevated apolipoprotein B, small LDL particles, insulin resistance and hyperinsulinemia, impaired glucose tolerance (IGT), elevated C-reactive protein (CRP), and variation in coagulation factors (eg, plasminogen activator inhibitor [PAI]-1 and fibrinogen). The conference on definition2 also emphasized that risk for type 2 diabetes is higher in persons with metabolic syndrome and that diabetes is a major risk factor for CVD. It also examined various criteria for a clinical diagnosis of the metabolic syndrome. The diagnostic scheme developed by ATP III is shown in the Table. Clinical criteria proposed by the World Health Organization3 and American Association of Clinical Endocrinologists4 also were reviewed. These latter criteria overlap with those of ATP III but differ by requiring direct evidence of insulin resistance for diagnosis. Both the World Health Organization and the American Association of Clinical Endocrinologists recommend an oral glucose tolerance test (OGTT) in patients without an elevated fasting glucose. In other words, in the absence of impaired fasting glucose (IFG), IGT detected by OGTT is considered as one metabolic risk factor defining the metabolic syndrome. ATP III does not recommend OGTT in such persons, even through IGT is a high-risk condition for type 2 diabetes (independent of IFG) and correlates with increased risk for CVD. ATP III, however, held that the information gained by OGTT does not outweigh its costs and inconvenience in routine practice. The present conference on management moved from the issue of definition of the metabolic syndrome to the wide issues of clinical management.