Independent associations between metabolic syndrome, diabetes mellitus and atherosclerosis: observations from the Dallas Heart Study

Diabetes mellitus (DM) has been termed a "coronary disease equivalent", yet data suggest that only those DM subjects with metabolic syndrome (MetS) are at increased coronary risk. Using data from the Dallas Heart Study, a large, probability-based population study, we assessed the individual and joint associations between MetS, DM and atherosclerosis, defined as coronary artery calcium (CAC) detected by electron-beam computerised tomography (EBCT) and abdominal aortic plaque (AAP) detected by magnetic resonance imaging. Among 2,735 participants, the median age was 44 years; 1,863 (68%) were non-white; 1,509 (55%) were women; 697 (25.5%) had MetS without DM; 53 (1.9%) had DM without MetS; and 246 (9.0%) had both DM and MetS. The prevalence of CAC increased from those with neither MetS nor DM (16.6%) to MetS only (24.0%) to DM only (30.2%) to both MetS and DM (44.7%) (p(trend) <0.0001). The prevalence of CAC was higher in those with both DM and MetS versus either alone (p<0.0001). After adjustment, MetS and DM were each independently associated with CAC (odds ratio [OR] 1.4, 95% confidence intervals [CI] 1.1-1.8; OR 1.8, 95% CI 1.3-2.5, respectively). Compared with the group without DM or MetS, those with both MetS and DM had the most CAC (adjusted OR 2.3; 95% CI 1.6-3.2). All analyses of AAP yielded qualitatively similar results. In conclusion, both MetS and DM are independently associated with an increased prevalence of atherosclerosis, with the highest observed prevalence in subjects with both DM and MetS.