Metabolic syndrome as an indicator of high cardiovascular risk in patients with diabetes: Analyses based on Korea National Health and Nutrition Examination Survey (KNHANES) 2008

Background: Patients with either diabetes mellitus (DM) or metabolic syndrome (MS) are recognized as a high risk group for cardiovascular disease (CVD). Several studies have demonstrated the clinical value of MS for predicting additional CVD risk in the DM population, although the clinical significance remains debatable. Methods: We used the Korea National Health and Nutrition Examination Survey (KNHANES) 2008, which is the national representative database. We classified the KNHANES subjects based on MS and glucose tolerance status, and compared clinical characteristics and future CVD risk among the subgroups. Results: A total of 796 of the 4314 subjects were diagnosed with MS. Their clinical characteristics were significantly different from patients without MS. Prevalence of DM was 9.5% in subjects with MS, but only 1.1% in subjects without MS. In addition, there was no MS in 30.9% of total DM patients who were enrolled in this study. For the normal and impaired fasting glucose subgroups, the prevalence of moderate (5-10%) and high (>10%) CVD risk was significantly higher in patients with MS than in patients without MS (p < 0.001). However, in the DM subgroup, even after multiple adjustments, there were no differences in clinical characteristics or in the prevalence of moderate to high CVD risk according to MS status. That said, LDL cholesterol in the DM group without MS was significantly higher than in the DM group with MS (p = 0.010). Conclusions: The efficacy of MS as a screening tool for high CVD risk may be limited in DM patients, and conventional risk factors such as LDL may be more important.