Does the Metabolic Syndrome Exist?

  1. Scott M. Grundy, MD, PHD123
  1. 1Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, Texas
  2. 2Department of Clinical Nutrition and Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
  3. 3Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
  1. Address correspondence and reprint requests to Scott M. Grundy, Center for Human Nutrition and Departments of Clinical Nutrition and Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Y3.206, Dallas, TX 75390-9052. E-mail: scott.grundy{at}utsouthwestern.edu

In recent years, several organizations have proposed that the metabolic syndrome be introduced into clinical practice as a multidimensional risk condition for both atherosclerotic cardiovascular disease (ASCVD) and type 2 diabetes (rev. in 1). This proposal generally has been well received. Recently, however, Kahn et al. (2) questioned whether evidence for the existence and characteristics of the metabolic syndrome is sufficiently developed to support its inclusion in clinical practice. Several critical issues were broached in their article. The present commentary will attempt to briefly respond to the issues raised.

Existence of the metabolic syndrome

Five risk factors of metabolic origin (atherogenic dyslipidemia, elevated blood pressure, elevated glucose, a prothrombotic state, and a proinflammatory state) commonly cluster together (1). This aggregation is frequently observed in clinical practice, and it has been convincingly documented in prospective studies by cluster analyses (3). Risk factor clustering cannot be explained by chance occurrence alone. Thus, if the metabolic syndrome is defined as multiple risk factors that are metabolically interrelated, then the syndrome certainly exists.

Appropriateness of the term “metabolic syndrome”

The commonly observed aggregation of metabolic risk factors has gone by several different names: syndrome X, insulin resistance syndrome, pre-diabetes, metabolic syndrome, dysmetabolic syndrome, plurimetabolic syndrome, cardiometabolic syndrome, dyslipidemic hypertension, hypertriglyceridemic waist, and deadly quartet (1). No single term has been universally accepted, and terminology likely will continue to be a topic of some disagreement. Kahn et al. have misgivings regarding whether the clustering of risk factors deserves the name “syndrome,” although most investigators are accepting of it. Among the various names, “metabolic syndrome” is widely used and broadly accepted in both cardiovascular and diabetes fields. It is general and does not commit to a particular pathogenesis. Consequently, it is reasonable to employ the term because of precedent and common usage. The term appears to be at least as good as any of the alternatives.

Unitary causation of the metabolic syndrome

For …

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