The Metabolic Syndrome: Requiescat in Pace

Values for insulin-mediated glucose disposal vary continuously throughout a population of apparently healthy individuals, with at least a sixfold variation between the most insulin sensitive and most insulin resistant of these individuals. The more insulin resistant a person, the more insulin must be secreted to prevent decompensation of glucose tolerance. Insulin resistance is not a disease, but a description of a physiologic state, and approximately one third of an apparently healthy population is sufficiently insulin resistant to be at increased risk to develop a cluster of abnormalities and related clinical syndromes. The primary value of the concept of insulin resistance is that it provides a conceptual framework with which to place a substantial number of apparently unrelated biological events into a pathophysiological construct. In contrast, the metabolic syndrome was introduced as a diagnostic category to identify individuals that satisfy three of five relatively arbitrarily chosen criteria to initiate lifestyle changes with the goal of decreasing risk of cardiovascular disease. Consequently, the value of the notion of the metabolic syndrome must be considered not in pathophysiologic terms, but as a pragmatic approach to obtain a better clinical outcome. In this review, an effort is made to critically evaluate the concept of the metabolic syndrome, the criteria chosen to identify individuals with the syndrome, and the clinical utility of making, or not making, a diagnosis of the metabolic syndrome.