Objective To investigate the cut-off point value of 1-hour plasma glucose of oral glucose tolerance test in the diagnosis of the T2DM and IGR.Methods Three hundred and fifty-four subjects (6.0mmol/L≤ FPG ＜ 7.0mmol/L) were participated in the OGTT.To get the cut-off point value of 1-hour plasma glucose in the diagnosis of the T2DM and IGR by applying the receiver operator characteristic curve,and compare it with the WHO diagnostic criteria.Results (1)The cut-off point value of screening T2DM by ROC curve was 12.90mmol / L,whose specificity was 77.1％ and sensitivity was 90％.Meanwhile the cut-off point value of screening IGR was 10.83mmol / L,whose specificity was 73.2％,and the sensitivity was 73.5％.(2)Among the 136 patients with type 2 diabetes mellitus that diagnosed by WHO criteria,115 patients could be diagnosed by 1hPG that more than FPG which could diagnose 81 patients.And the difference was statistically significant (P ＜ 0.05).Meanwhile,It was more than 106 patients that diagnosed by 2hPG,but there was no statistically significant.According to the diagnostic criteria of 2hPG ≥11.1mmol/L,there were 106 cases of T2DM.Among these patients,95 cases and 51 cases could be diagnosed respectively by 1 hPG and FPG,and there was statistically significant (P ＜ 0.01).(3)Application of the cut-off point of 1 hPG,NGT,IFG,CGI and DM re-grouped.FPG,2hPG increased gradually in order to NGT,IGR,DM.(4) No matter the blood glucose levels,1hPG and 2hPG had good correlation,(P =0.000).A significant correlation could be found between FPG and 2hPG only in hyperglycemia.The correlations between 1 hPG and FPG disappeared only in a normal level of blood glucose.Conclusion The cutoff point value of 1hPG is 12.90mmol/L which has advantage to diagnosis of type 2 diabetes mellitus.It is a useful complement to the WHO Diagnostic criteria.