title: Diagnostic efficiency of hemoglobin A1c for newly diagnosed diabetes and prediabetes in community-based Chinese adults aged 40 years or older.
abstract: BACKGROUND
  Europeans and Americans are gradually accepting the hemoglobin A1c (HbA1c) threshold of 6.5% for diagnosing diabetes proposed by the American Diabetes Association, but the cutoff of HbA1c for the Chinese population is unclear. We evaluated the diagnostic efficiency of HbA1c for diagnosing newly diagnosed diabetes and prediabetes in community-based Chinese adults 40 years of age or older.
  
  
  METHODS
  In this study 8,239 subjects (5,496 women) 40-90 years of age underwent HbA1c and oral glucose tolerance test measurement after an overnight fast. Diabetes and prediabetes were defined by the World Health Organization criteria. The area under the receiver operating characteristic curve (AUC) was used to evaluate the diagnostic efficiency of HbA1c, and the optimal cutoff was defined as the point on the receiver operating characteristic curve with the largest Youden index. Spearman correlation was used for correlation analysis.
  
  
  RESULTS
  The prevalence of newly diagnosed diabetes and prediabetes was 10.7% (880/8,239) and 19.0% (1,564/8,239), respectively. Fasting plasma glucose and postprandial plasma glucose were positively correlated with HbA1c level (r=0.725 and r=0.673, both P<0.001, respectively). For diagnosing diabetes, the AUC was 0.857 (95% confidence interval, 0.841-0.873), and the optimal cutoff for HbA1c was 6.3%, with the largest Youden index being 0.581. For diagnosing prediabetes, the AUC was 0.681 (95% confidence interval, 0.666-0.697), and the optimal cutoff for HbA1c was 5.9%, with the largest Youden index being 0.280.
  
  
  CONCLUSIONS
  An HbA1c threshold of 6.3% was highly valuable for diagnosing newly diagnosed diabetes, and a value of 5.9% was weakly valuable for diagnosing prediabetes in community-based Chinese adults 40 years of age or older.
authors.affiliation: 1 Department of Endocrinology of Qilu Hospital and Institute of Endocrinology and Metabolism, Shandong University , Jinan, China .
authors.forename: Kai
authors.initials: K
authors.lastname: Liang
authors.forename: Yu
authors.initials: Y
authors.lastname: Sun
authors.forename: Wen-juan
authors.initials: WJ
authors.lastname: Li
authors.forename: Xiu-ping
authors.initials: XP
authors.lastname: Zhang
authors.forename: Cheng-qiao
authors.initials: CQ
authors.lastname: Li
authors.forename: Wei-fang
authors.initials: WF
authors.lastname: Yang
authors.forename: Ze-qiang
authors.initials: ZQ
authors.lastname: Ma
authors.forename: Ai-xia
authors.initials: AX
authors.lastname: Ma
authors.forename: Hui-zhen
authors.initials: HZ
authors.lastname: Zheng
authors.forename: Jun
authors.initials: J
authors.lastname: Song
authors.forename: Peng
authors.initials: P
authors.lastname: Lin
authors.forename: Xin-guo
authors.initials: XG
authors.lastname: Hou
authors.forename: Li
authors.initials: L
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose / Q000032:analysis; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000208:ethnology; D003937:Diagnosis, Differential; D005260:Female; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000032:analysis*; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period; D017410:Practice Guidelines as Topic; D011236:Prediabetic State / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000208:ethnology; D015995:Prevalence; D012680:Sensitivity and Specificity
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human