Objective: Data on the clinical usefulness of the metabolic syndrome with respect to cardiovascular risk are not conclusive. We have assessed this issue in a large population-based cohort of diabetic and nondiabetic people in Southern Europe.
Methods: An Italian population-based cohort of 3729 individuals (2211 without diabetes and 1518 with diabetes) was examined, with centralized measurements, including the Homeostasis Model Assessment (HOMA) index in nondiabetic people. The usefulness of the metabolic syndrome (ATP III criteria) as an indicator of cardiovascular disease (CVD), independently of classical and novel risk factor [C-reactive protein (CRP) and albumin excretion rate (AER)] was assessed by using unconditional logistic regression.
Results: One thousand, seven hundred and fifty-three individuals (47.0%) had neither diabetes nor the metabolic syndrome, 458 (12.3%) had the metabolic syndrome only, 442 (11.8%) had type 2 diabetes only and 1076 (28.9%) had both diabetes and the metabolic syndrome. The highest likelihood of having CVD was conferred by both diabetes and the metabolic syndrome [odds ratio (OR) = 4.37, 95% confidence interval (CI) 3.25-5.87], independently of age, sex, low-density lipoprotein-cholesterol, smoke, AER, and CRP values. After further adjustment for its individual components, the association between CVD and the metabolic syndrome was no more evident. Among people with CRP 3 mg/l or less, ORs were similar in nondiabetic people with the metabolic syndrome and in diabetic people without it, whereas among those with CRP greater than 3 mg/l OR was two-fold higher in the latter. Values in upper quartiles of the HOMA-IR conferred a significant two-fold increased OR of CVD, even after adjustment for individual components of the metabolic syndrome, CRP and AER.
Conclusions: The additional information provided by the metabolic syndrome is limited, in both diabetic and nondiabetic people, whereas the HOMA index is a useful indicator of CVD, independently of individual components of the metabolic syndrome, classical and novel risk factors.