Probable blind spot in the International Diabetes Federation definition of metabolic syndrome

Objectives: The International Diabetes Federation (IDF) proposed a novel definition of the metabolic syndrome (MS) in 2005, which designated central obesity as mandatory. The new National Cholesterol Education Program (NCEP) version, announced by the American Heart Association and National Heart Lung and Blood Institute in October 2005, did not favor any of the five components. We set out to compare the cardiovascular profiles of patients cross-defined by these two definitions to shed light on the differential meanings of the two. Research Methods and Procedures: We analyzed data from 2608 non-institutionalized adults (>= 19 years old) in the National Nutrition and Health Survey in Taiwan, who had complete data for the five MS defining components. Both definitions adopted lower cut-points for fasting glucose and race-specific cut-points for waist circumference. Results: Under the IDF's and new NCEP's definitions, the MS prevalence was 6.2% and 11.6% in men and 12.6% and 16.5% in women, respectively. Although the two definitions had high agreement, IDF failed to pick up similar to 4% to 5% of people with more than three MS component disorders but a waist circumference less than the cut-point. Subjects whose physical conditions only satisfied NCEP's definition had similar or worse metabolic profiles than those whose conditions satisfied both IDF's definition and the new NCEP's definition. Discussion: The IDF definition would fail to identify a portion of people who have more than three MS component disorders but a small waistline. Further research and discussion are needed on whether and how to implement the IDF's definition.