Preliminary Study On The Cut-off Point Of Glycosylated Hemoglobin A1c In Diagnosis Of Diabetes Mellitus In Han Nationality In Xining Area

Objective: To study the diagnosis of diabetes mellitus(DM)by glycosylated hemoglobin A1c(Hb A1c)in the Han population of Xining,and to explore whether there is a Hb A1 c cut-point value which is more suitable for the diagnosis of DM in this area.Methods: During the period from December 2014 to December 2016,the Han nationality in the Xining area was undiagnosed diabetes mellitus or in high-risk groups,in inpatient department of Affiliated Hospital of Qinghai University.There were 565 males,319 males and 246 females with an average age of 57±14 years.Oral glucose tolerance test(OGTT)was performed on the subjects and Hb A1 c was determined.With OGTT as the gold standard for diagnosis of DM,the receiver operating characteristic curve(ROC)was drawn by SPSS software,and the optimal Hb A1 c cut-off point of the diagnosis DM was determined.Results:(1)According to the standard of WHO diagnosis for DM in 1999,there were 233 cases,103 cases and 229 cases of normal glucose tolerance(NGT),impaired glucose regulation(IGR)and DM in all the study groups.(2)The optimal cut-off point for the diagnosis of DM in Han nationality in Xining area is 6.35%,the area under the curve is 94%(95% confidence interval,0.92~0.96),the sensitivity is 86.9%,specificity 86.9%,the positive predictive value of 81.5%,negative predictive value 90.7%,positive likelihood ratio 6.63,negative likelihood ratio 0.15.(3)The Hb A1 c cut-off value of 6.35% sensitivity higher than that of Hb A1c?6.5% and fasting plasma glucose(FPG)greater or equal to 7.0mmol/L(86.9%>84.3%>65.1%).(4)With Hb A1c?6.35% and Hb A1c?6.5% of all the subjects in this study as the criteria for the diagnosis of diabetes mellitus,the detection was the result of diabetes mellitus,the difference was statistically significant(P=0.031).(5)Hb A1 c 6.35% and 6.5% of the two different cut-off point values to detect whether the results of DM by Kappa consistency test,there is a high consistency(Kappa index = 0.977).(6)The levels of red blood cell and hemoglobin in DM group were significantly higher than those in IGR group and NGT group(P <0.05).Conclusion:(1)In this study,the optimal cut-point for Hb A1 c diagnosis of DM in Han nationality of Xining area is 6.35%.(2)When you can not detect FPG or FPG can not really reflect the immediate blood glucose,you can refer to the results of Hb A1 c test.