Discussion on the HbA_1c screening its for diagnostic cut-point of diabetes mellitus

Objective To evaluate the hemoglobin A1c(HbA1c) screening in diagnosing diabetes mellitus and identify the optimal HbA1c cut-point for diagnosing diabetes mellitus in Chinese adults.Methods A cross-sectional analysis on 1280 adults without known diabetes and impaired glucose regulation obtained from the Health Examination Center and the Out-patient Department of Anhui Provincial Hospital was conducted.All of them received an oral glucose tolerance test(OGTT) and the measure of HbA1c,and their BMI,SBP,DBP,TC,TG and so on.The optimal HbA1c threshold for diagnosing diabetes mellitus was identified with the ROC curve.Results The HbA1c levels of the NGT,IGR,and DM groups were(5.50±0.35)%,(5.91±0.56)%,and(7.38±1.52)% respectively,being statistically different(P0.05).According to ROC,the optimal cut-off point of HbA1c for the diagnosis of diabetes was 6.1%,and its sensitivity was 90.9% and specificity 86.4%.No matter what diagnostic method of OGTT or HbA1c≥6.1%,the newly diagnosed diabetic patients' age,BMI,BP,and blood lipid were not statistically different.Compared with the result of OGTT,the 6.6% NGT(n=56) and 37.1% IGR(n=93) subjects had an HbA1c≥6.1%.The cut-off point HbA1c≥6.5% in the ADA criteria showed a very high specificity(96.1%) and a corresponding sensitivity 71.0%.Conclusions The optimal cut-off point of HbA1c for the screen of diabetes is 6.1%,which showed higher sensitivity and lower specificity than the HbA1c threshold 6.5%.