Optimum Fasting Plasma Glucose Cut Points to Screen Diabetes in China

To find the optimal fasting plasma glucose (FPG) cut point for diagnosis of prediabetes and diabetes in China. 2855 adults (age ranged 18-76 years; 1123 males, 1732 females) entered into this analysis, of which 2267 were normal glucose tolerance (NGT), 324 were isolated impaired glucose tolerance (IGT), and 95 diabetes had isolated increased 2-hour plasma glucose levels. Sensitivity, specificity, positive predictive values and negative predictive value were computed at 10-units increments of FPG. Performance of the FPG value to screen for diabetes was analyzed based on the receiver operating characteristic (ROC) curve. After adjusting for age, fasting plasma glucose FPG, 2 hour plasma glucose (2h-PG), body mass index (BMI), triglyceride (TG), uric acids (UA) showed an increasing trend from NGT group, IGT group to newly diagnosed diabetes group.The optimal FPG cut points for diabetes would be 5.55mmol/L. At this point, Youden index was the highest sensitivity was 81.5% which approximated specificity.For diagnosing prediabetes, FPG cut point at 4.99mmol/L had the highest Youden index, and the misdiagnosed rate was ranged from 33.0% to 35.8%.At FPG cut values of 4.99, 5.55, 6.10mmol/L, 2-h PG were significantly higher in prediabetes with FPG below the value than FPG at or above the value.Our analysis suggested that optimal FPG cut point for diagnosing diabetes might be 5.55mmol/L and for diagnosing prediabetes may be 4.99mmol/L.