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.

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 investigation 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 = 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 > or =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 significantly 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.

Effects of metformin on glucagon-like peptide-1 levels in obese patients with and without Type 2 diabetes.

Metformin has been shown to increase glucagon-like peptide-1 (GLP-1) levels after an oral glucose load in obese non-diabetic subjects. In order to verify if this effect of the drug was also present in obese Type 2 diabetic patients who have never been treated with hypoglycemic drugs, 22 Type 2 diabetic and 12 matched non-diabetic obese patients were studied. GLP-1 was measured before and after a 100 g glucose load at baseline, after a single oral dose of 850 mg of metformin, and after 4 weeks of treatment with metformin 850 mg three times daily. Post-load GLP-1 levels were significantly lower in diabetic patients. A single dose of metformin did not modify GLP-1 levels. After 4 weeks of treatment, fasting GLP-1 increased in diabetic patients (3.8 vs 4.9 pmol/l; p<0.05), while the incremental area under the curve of GLP-1 significantly increased in both diabetic [93.6 (45.6-163.2) vs 151.2 (36.0-300.5) pmol x min/l; p<0.05] and non-diabetic [187.2 (149.4-571.8) vs 324.0 (238.2-744.0) pmol x min/l; p<0.05] subjects. In conclusion, GLP-1 levels after an oral glucose load in obese type 2 diabetic patients were increased by 4 weeks of metformin treatment in a similar fashion as in obese subjects with normal glucose tolerance.