Comparison of the Prevalence of the Metabolic Syndrome by WHO, AHA/NHLBI, and IDF Definitions in a German Population with Type 2 Diabetes: The Diabetes in Germany (DIG) Study

This study investigated the prevalence of the metabolic syndrome (MetS) in a German population with type 2 diabetes (T2DM) using the three definitions for MetS according to WHO 1999, AHA/NHLBI 2005, and IDF 2005 criteria. Fourthousand and twenty participants as a cross section of daily practice of diabetes care in Germany (238 unselected sites) were included in the Diabetes in Germany (DIG) study. Inclusion criteria: T2DM and age between 35-80 years. Exclusion criteria: major cardiovascular event <3 months before entry, NYHA-IV, macroproteinuria, and cancer < 5 years before entry. The components of MetS were measured following a standard protocol for anthropometric and laboratory control. The average diabetes duration was 8.4 years and HbA 1c 7.0%. The prevalence of MetS by WHO criteria was 26.1 %, by AHA/NHLBI 79.3%, and by IDF 82.6%. The degree of agreement (kappa statistic) was kappa=0.69 between AHA/NHLBI and IDF definitions, but only 0.12 for WHO vs. IDF, and 0.17 for WHO vs. AHA/NHLBI. The frequency of central obesity by WHO was 50.9%, by AHA/ NHLBI 72.9%, and by IDF 92.0% and for hypertension 29.3%, 92.6%, and 92.6%, respectively. However, the frequencies of lipid components by the three definitions were in the same range (57.8%, 59.5%, 59.5%). In this representative German sample of patients with type 2 diabetes, the prevalence of MetS was very highly independent of using the IDF or AHA/NHLBI definition. Females were significantly more affected than males. The distinctly lower prevalence delineated from WHO criteria is due to low frequency of central obesity and hypertension as consequence of higher cutoff limits for these components used in the WHO definition.