Dr Bernhard Ludvik (Medical University of Vienna, Austria), who presented the results of the analysis during the European Association for the Study of Diabetes 2008 Meeting, told heartwire "I think it was a bit premature to launch a new diagnosis for metabolic syndrome. If you want to assess the risk of developing type 2 diabetes, it's best to stick with the NCEP ATP III criteria."

Dr Bernhard Ludvik

Ludvik and colleagues collected parameters relevant to the diagnosis of metabolic syndrome in 13 852 nondiabetic subjects (mean age 45) and then followed them for an average of six years. Using the IDF definition of metabolic syndrome, 13.3% of the cohort had metabolic syndrome at baseline, whereas the overall number according to the NCEP III definition was just 10.4%. Of note, concordance between the two definitions was "modest," Ludvik said, expressed by a kappa value of 0.63.

When metabolic-syndrome diagnosis was correlated with subsequent development of diabetes over the follow-up period, both definitions were found to be associated with an increased relative risk of developing type 2 diabetes. In men, the relative risk for both definitions was similar and not statistically different; however, in women, the NCEP III definition was associated with a higher relative risk of developing diabetes.

Ludvik et al concluded that while the prevalence of metabolic syndrome in nondiabetic subjects was higher when the IDF definition was used, the NCEP criteria, at least in women, "allow a better assessment of the risk for type 2 diabetes," Ludvik said.

To heartwire, Ludvik hypothesized that because the NCEP criteria are more broadly focused on specific cardiovascular risk factors, they may have performed better in this particular group, which he said had a higher prevalence of risk factors such as hypertension and hyperlipidemia—the women in particular. But Ludvik also suggested that the rapid adoption of the IDF criteria was "driven by external factors," particularly pressure from industry to give particular emphasis to waist circumference. Before this definition is used more widely, Ludvik believes it should be better validated not only for the prediction of type 2 diabetes, but also subsequent cardiovascular disease.

In his own practice, he says he never uses the IDF criteria. Asked whether he discusses the differences between the two definitions with his patients, Ludvik pointed out: "Patients don't care about metabolic syndrome, as long as they don't have diabetes."