Objective To explore the value of serum 1,5-AG in the diagnosis of diabetes mellitus by applying the method of pyranose oxidase (PROD). Methods 1,5-AG,FPG、2hPG and HbA_1c were determined in 50 case of DM,100 case of IGT and 30 control subject. ROC curve was applied to evaluate the diagnostic efficiency of 1,5-AG,FPG and HbA_1c for DM. Results Serum 1,5-AG was obviously lower in the diabetes than in IGT and controls(P＜0.01). Compared with controls, IGT patients had lower serum 1,5-AG(P＜0.05).1,5-AG level had significantly negative correlation with FPG,2hPG and HbA_1c respectively. The area under the ROC curve of 1,5-AG,FPG and HbA_1c are 0.948、0.921、0.817,respectively. Conclusions 1,5-AG level shows significantly correlation with glucose tolerance. Serum 1,5-AG measurement could be used as useful indicator in the screening of diabetes mellitus as well as in the monitoring of glycemic control.