Is the Metabolic Syndrome Really a Syndrome?

The metabolic syndrome: time for a critical appraisal: joint statement from the American Diabetes Association and the European Association for the Study of Diabetes. Diabetes Care 28:2289–2304, 2005.

The term "metabolic syndrome" has been widely used in research to refer to a combination of related health factors that, when they appear together, create a higher risk for heart disease. Each of the various factors of the syndrome -- by various definitions, these include diabetes, insulin resistance, obesity, unhealthy lipid (types of fat in the blood vessels, such as cholesterol and triglycerides) levels, high blood pressure, and signs of kidney disease -- is already known to increase the risk for heart disease.

A key question is whether the presence of the metabolic syndrome, by any definition, shows a greater risk for heart disease than the risks posed by each of the individual health factors mentioned above.

According to a joint statement by the American Diabetes Association and the European Association for the Study of Diabetes, the answer is "no."

The authors state there is no solid evidence that any of the metabolic syndrome health factors contribute more together than they do individually. In other words, the whole is not greater than the sum of its parts. The metabolic syndrome hasn't been properly defined in previous research, and it should not be treated as a unique syndrome until the science behind it is clear. Each of the health factors mentioned above put people at risk for heart disease and should be treated as such, but the combination of these factors should not be considered, or treated as, a separate disease.

In conclusion, the authors recommend that doctors should:

• Aggressively treat the individual health factors that lead to heart disease (diabetes, insulin resistance, unhealthy triglyceride and cholesterol levels, high blood pressure, and signs of kidney disease)
• Continue to evaluate patients for other risks that can lead to heart disease
• Avoid labeling patients with the term "metabolic syndrome"
• Avoid prescribing a treatment for the "syndrome" until new, solid evidence is found.