Association of the metabolic syndrome and insulin resistance with silent myocardial ischemia in patients with type 2 diabetes mellitus

Metabolic syndrome is associated with elevated morbidity and mortality for overt coronary artery disease (CAD). In diabetic patients, CAD is often silent. The relation between metabolic syndrome and silent CAD has never been studied. We investigated whether metabolic syndrome is associated with silent CAD in patients with type 2 diabetes mellitus. We evaluated the prevalence of metabolic syndrome in 169 patients with uncomplicated diabetes and angiographically verified silent CAD and in 158 diabetic patients without myocardial ischemia on exercise electrocardiography, 48-hours ambulatory electrocardiography, and stress echocardiography. The groups were comparable for gender, age, glycemic control, and diabetes duration. Metabolic syndrome was defined according to the National Cholesterol Education Program criteria. To estimate insulin resistance in patients treated with diet alone or oral agents (122 patients with CAD and 115 patients without CAD), the Homeostasis Model Insulin-Resistance Assessment (HOMA) was used. The prevalence of metabolic syndrome (59.8% vs 44.3%, p = 0.005) and HOMA (5.4 +/- 2.1 vs 4.9 +/- 2.8, p = 0.044) were significantly higher in those with CAD than in those without CAD. Multiple logistic regression analysis showed that the metabolic syndrome was associated with silent CAD (odds ratio 2.44, 95% confidence interval 1.19 to 5.02, p = 0.015). Among patients on diet alone or oral agents, the HOMA was the strongest predictor of silent CAD (odds ratio 10.16, 95% confidence interval 2.60 to 39.63, p < 0.001). In conclusion, our data have shown an independent association of metabolic syndrome and insulin resistance with silent CAD in patients with type 2 diabetes mellitus. Other studies are needed to establish whether metabolic syndrome and HOMA are reliable markers to identify diabetic patients for additional screening for silent CAD.