A meta-analysis* of 87 studies involving 951,083 patients, performed by a Canadian research team, shows that the pre-diabetic condition known as metabolic syndrome increases the risk of heart disease or stroke in patients by a factor of more than two.
Metabolic syndrome, which afflicts an estimated 25 percent of all North Americans, is a cluster of conditions that are considered precursors to type 2 diabetes. While they include obesity (often produced by a sedentary lifestyle), the metabolic syndrome elements most closely associated with a high risk of cardiovascular disease are high blood sugar (which can inflame blood vessels), high blood pressure, and high levels of LDL, or “bad,” cholesterol.
The nine-person research team, from McGill University, Jewish General Hospital, and Laval Hospital, all in Quebec, conducted the meta-analysis to help settle a question: Can metabolic syndrome by itself, without developing into full-blown diabetes, increase a person’s risk of heart disease or stroke? If so, by how much?
The study analyzed data using two sets of definitions of cardiovascular risk, from the U.S.-developed 2001 National Cholesterol Education Program and the 2004 revised National Cholesterol Education Program. The team reconciled slight differences in the definitions to reach its conclusions.
While the researchers concluded that there is a definite link between metabolic syndrome and higher risk of cardiovascular disease, it did not establish how metabolic syndrome increases that risk. Another unanswered question is whether metabolic syndrome poses a higher overall risk than its individual components put together. For example, if high blood pressure, high blood sugar, and high “bad” cholesterol increase the risk of cardiovascular disease by X, Y, and Z percent, respectively, does their cumulative percentage equal that of metabolic syndrome?
The Canadian team’s results, published in the September 28, 2010, Journal of the American College of Cardiology, bolster concerns that even if people with metabolic syndrome do not move on to fully developed type 2 diabetes, they are already at high risk of heart disease or stroke.
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*A meta-analysis synthesizes the results of many research studies that address a related topic.