The ROC analysis for different time points during oral glucose tolerance test

This purpose was to discuss optimal reference value for normal glucose tolerance (NGT) at different time points during an oral glucose tolerance test (OGTT) by receiver operating characteristic (ROC) analysis. One thousand seven hundred and forty-six subjects from March 2004 to March 2005 were given 75 g OGTT and the blood samples were collected at 0, 30, 60, 120 and 180 min for glucose measurement. Other demographic data (e.g. age, sex, body mass index, BMI) were also recorded. The status of NGT, impaired glucose tolerance (IGT), impaired fasting glucose (IFG) and DM was determined according to American Diabetes Association (ADA) criteria. IGT and IFG were merged as impaired glucose regulation (IGR). Using IGR as the assumed test, the cutoff values at 0, 30, 60, 120 and 180 min during OGTT for normal reference range were calculated by ROC analysis. The cutoff values were 5.6, 9.5, 10.1, 7.8 and 6.1 mmol/l at 0, 30, 60, 120 and 180 min, respectively, in whole subjects. In addition, we provided the ROC information in age-stratified groups since there are differences among different age groups. When the results of OGTT were considered, the present study provided a reference range value to evaluate the status of glucose tolerance. Because of the heterogeneity of diabetes, further studies are necessity. And the sample collection is continuing.