To evaluate the usefulness of the metabolic syndrome in predicting onset of diabetes and cardiovascular disease (CVD), researchers reviewed two large prospective studies in which baseline data were collected from older men on all five metabolic-syndrome components (body-mass index, triglyceride level, HDL cholesterol level, fasting glucose level, blood pressure). These studies provided outcome data on incident CVD and type 2 diabetes. In the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER; JW Jan 7 2003), 4218 older patients (age range, 70–82) with vascular disease or high risk for vascular disease received pravastatin or placebo and were followed for a mean of 3.2 years. In the observational population-based British Regional Heart Study (BRHS; BMJ 1981; 283:179), 2737 older men (age range, 60–79) were followed for a mean of 7 years. Data on participants with baseline diabetes were excluded.
Baseline prevalence of metabolic syndrome was 28% in PROSPER and 27% in BRHS. In both PROSPER and BRHS, metabolic syndrome was associated strongly with risk for new-onset diabetes (relative risks, 4.41 and 7.47, respectively). However, high fasting glucose levels (
110 mg/dL), with or without other components, also predicted diabetes onset (RRs, 18.42 and 5.97, respectively). Metabolic syndrome was associated only weakly with incident CVD in BRHS (RR, 1.27) and was not associated at all in PROSPER. In BRHS, adjustment for Framingham risk scores eliminated the association between metabolic syndrome and CVD.Comment: An editorialist calls this study "another nail in the coffin of the metabolic syndrome." Fasting hyperglycemia alone was a much stronger predictor of incident diabetes than were the combined metabolic-syndrome components. Similarly, the Framingham risk score, which includes important nonmetabolic factors such as smoking, was a strong independent predictor of cardiovascular disease, whereas the metabolic syndrome was not. The concept of the metabolic syndrome has been useful in suggesting common pathophysiological pathways, but little evidence shows that diagnosing the syndrome adds value in clinical decision making.
— Bruce Soloway, MD
Published in Journal Watch General Medicine July 29, 2008