Optimal Cut-off Points of BMI WC and WHR for Screening of Pre-Diabetes and Diabetes Over 35 Years Old People

Using BMI, WC and WHR to investigate and compare these screening tool for IFG, IGT and diabetes subjects in Shanghai China; and to identify the optimal cut-off points of BMI, WC and WHR for screening pre-diabetes (Pre-DM) and diabetes (DM) over 35 years old people. Totally 3,195 aged 35 years old and above people who attended community epidemiological survey of diabetes mellitus. Using ADA criteria (2010), the participants were classified as normal, Pre-DM or DM according to test results of blood glucose. The area under ROC curve (AUROC) for BMI, WC and WHR were calculated; as well as the sensitivity, specificity and Youden index under different BMI or WHR cut-off points. Among these people, age is (61.07±10.08), and BMI and WHR are respectively (25.12±3.29) and (0.87±0.06). The positive rate of screening of DM is 11.36% and that of Pre-DM is 38.57%. There are correlation between blood glucose and BMI or WHR (p<0.05). With the increase of BMI or WHR cut-off point, the screening sensitivity (YI, Sp and Se) for DM or pre-DM are decreasing; but the area under ROC (AUROC) increases firstly and then decreases (inflection point: WHR≥0.8~0.9 and BMI≥23 for pre-DM, WHR≥0.9 and BMI≥24 for DM). The combined screening efficacy of BMI merged WHR is the best combination choice (cut-off point of BMI and WHR are respectively 23 and 0.8), and YI is the highest. Using HbA1C as standard of judgment seems to be better than blood glucose in screening for DM. BMI≥23, WC≥90 cm or WHR≥0.8 is the optimal cut-off point for screening DM and pre-DM, and the screening efficacy of BMI is better than WC and WHR. BMI merged WHR is the best combination choice (cut-off point of BMI and WHR are respectively 23 and 0.8). HbA1C is better than FBG and OGTT as standard of judgment in screening.