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It's All About the Blood Pressure -- Trial Results, Guidelines, Journals, Risk Factors, and Drugs: US and European Diabetes Organizations Question Existence of Metabolic Syndrome


US and European Diabetes Organizations Question Existence of Metabolic Syndrome

A joint statement issued by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) has called into question the existence of the metabolic syndrome, the cluster of risk factors, including hypertension, that is widely believed to predict the risk of developing cardiovascular disease. The ADA/EASD statement, published simultaneously in the September issue of Diabetes Care and in Diabetologia,[13] argues that the metabolic syndrome is poorly defined, inconsistently used, and in need of further research to help understand whether and how it should be treated. There is "a lack of certainty regarding its pathogenesis," and "considerable doubt regarding its value as a cardiovascular disease risk marker," the statement says. Physicians, according to the authors, should not be diagnosing people with this "syndrome" or attempting to treat it as a separate malady until the science behind it is clear.

Since it was first described in 1998,[14] the metabolic syndrome has been defined differently by a number of organizations, including the WHO,[15] the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III),[16,17] and, most recently, the International Diabetes Federation (IDF).[18]

According to the WHO definition, for diagnosis of the syndrome a patient must present with glucose intolerance, impaired glucose tolerance, or diabetes and/or insulin resistance plus 2 or moreadditional risk factors: central obesity, high triglycerides or low HDL cholesterol; high blood pressure (≥ 140/90 mmHg); and microalbuminuria.

Diagnosis according to the ATP III criteria is by 3 or more of 5 risk factors: central obesity, high triglycerides, high blood pressure (≥ 130/85 mmHg), low HDL cholesterol, and high blood glucose.

The IDF definition is based on central obesity plus 2 of 4 factors: high triglycerides, low HDL cholesterol, high blood pressure (≥ 130/85 mmHg or antihypertensive treatment), and high fasting blood glucose or diabetes.

The ADA/EASD statement says that the fact that these definitions conflict implies that there is no clear evidence base for what should or should not be included. It says that the criteria for the syndrome are ambiguous and incomplete and that the rationale for thresholds are ill-defined; the value of including diabetes in the definition is questionable; insulin resistance as the unifying etiology is uncertain, and there is no clear basis for including/excluding other cardiovascular disease risk factors.

The cardiovascular risk associated with the "syndrome" appears no greater than the sum of its parts, according to the statement. Treatment of the "syndrome" is no different from treatments for each of its components and in patients with diabetes or known vascular disease, and inordinate attention to the "syndrome" can impede appropriate care, the authors believe. People should not be diagnosed with the "metabolic syndrome," as doing so will mislead the patient into believing that he or she has a unique disease, instead of well-known cardiovascular risk factors, the authors state.

The authors of the statement believe that "the metabolic syndrome requires much more study before its designation as a 'syndrome' is truly warranted and before its clinical utility is adequately defined." They recommend that doctors continue to evaluate patients for the presence of other cardiovascular risk factors when one is discovered; aggressively treat individual cardiovascular risk factors; avoid labeling patients with the term "metabolic syndrome;" and not attempt to prescribe a treatment for this "syndrome" until new, solid evidence is obtained.

The metabolic syndrome has also recently been declared "dead" by the man who originated the concept (as "Syndrome X"), Gerald Reaven, MD (Stanford University School of Medicine; Stanford, California).[19,20] Dr. Reaven has declared himself "unimpressed" by both the WHO and ATP III forms of the metabolic syndrome. He believes that physicians should focus on individual cardiovascular disease risk factors instead of whether or not individuals are obese or whether they meet a certain number of criteria for making a diagnosis of the metabolic syndrome. However, Scott M. Grundy, MD (University of Southwest Medical Center; Dallas, Texas), who was a member of the team that issued the ATP III criteria as well as a consultant to the group that developed the IDF definition, replied that he see still sees "signs of life" in the concept, which "represents a powerful hypothesis that unifies the metabolic factors underlying the development of both atherosclerotic cardiovascular disease and diabetes" and "a useful clinical tool."[21]

A recent analysis applying ATP III criteria estimated that approximately 24% of adults in the United States have the metabolic syndrome.[22]