ORIGINAL ARTICLE doi: 10.1111/j.1463-1326.2007.00724.x National Cholesterol Education Program and International Diabetes Federation definitions of metabolic syndrome in the prediction of diabetes. Results from the FIrenze-Bagno A Ripoli study E. Mannucci, 1 M. Monami, 1 B. Cresci, 2 L. Pala, 2 G. Bardini, 2 M. G. Petracca, 2 I. Dicembrini, 2 A. Pasqua, 3 E. Buiatti 3 and C. M. Rotella 2 1 Diabetes Section, Geriatric Unit, Department of Critical Care, University of Florence, Florence, Italy 2 Endocrine Unit, Department of Clinical Pathophysiology, University of Florence, Florence, Italy 3 Epidemiology Unit, Local Health Unit 10, Florence, Italy Background: The International Diabetes Federation (IDF) proposed to modify the diagnostic criteria for metabolic syndrome (MS) previously issued by the National Cholesterol Education Program (NCEP). Aim of the present inves- tigation is to compare the predictive value for diabetes of NCEP and IDF definitions of MS in a large sample of predominantly Caucasian subjects. Methods: A prospective observational study was performed on a cohort study (n ¼ 3096) enrolled in a diabetes- screening programme, the FIrenze-Bagno A Ripoli study. All subjects with fasting glucose >126 mg/dl and/or post-load glucose 200 mg/dl (5.7%) were excluded from the present analysis. Follow-up of each subject was continued until diagnosis of diabetes, death or until 31 December 2005. Mean follow-up was 27.7  11.3 months. Results: Among subjects enrolled, 13.7 and 25.2% were affected by MS using NCEP and IDF criteria respectively. During follow-up, 38 new cases of diabetes were diagnosed, with a yearly incidence rate of 0.5%. The relative risk for diabetes in subjects with MS was 10.10 [5.13; 20.00] and 7.87 [3.70; 16.7] using NCEP and IDF definitions respectively. After adjustment for age, sex, fasting glucose and waist circumference, NCEP-defined MS, but not IDF-, was signifi- cantly associated with incident diabetes (hazard ratio, 95% CI: 2.41 [1.01; 5.95] and 2.05 [0.80; 5.29] respectively). Conclusions: Although the reasons for the proposed changes in diagnostic criteria for MS are easily understandable, the newer IDF definition, while increasing estimates of prevalence of the syndrome, reduces the effectiveness of MS in identifying subjects at risk for diabetes. Further research is needed before the previous NCEP criteria are abandoned. Keywords: diabetes, metabolic syndrome, obesity Received 2 December 2006; returned for revision 2 February 2007; revised version accepted 7 February 2007 Background and Aims The International Diabetes Federation (IDF) proposed to modify the diagnostic criteria for metabolic syndrome (MS) previously issued by the Adult Treatment Panel III of the National Cholesterol Education Program (NCEP) [1,2]. The threshold for fasting glucose and waist cir- cumference was lowered, and abdominal adiposity was Correspondence: Carlo Maria Rotella, MD, Section of Endocrinology, Department of Clinical Pathophysiology, University of Florence, Viale Pieraccini 6, 50139 Florence, Italy. E-mail: c.rotella@dfc.unifi.it 430 j Diabetes, Obesity and Metabolism, 10, 2008, 430–435 # 2007 The Authors Journal Compilation # 2007 Blackwell Publishing Ltd