title: Glycated haemoglobin A₁c for diagnosing diabetes in Chinese subjects over 50 years old: a community-based cross-sectional study.
abstract: OBJECTIVE
  Little is known about using glycated haemoglobin A₁c (HbA₁c) to diagnose diabetes in Chinese subjects over 50 years old. This study aims to evaluate HbA₁c in diagnosing diabetes and identify the optimal threshold to be used in Chinese community subjects aged over 50 years.
  
  
  METHODS
  A community-based cross-sectional survey was conducted from October 2010 to January 2011 in Shipai community of Guangzhou, Guangdong, China. A total of 1494 subjects (72·8%) aged over 50 years were investigated. Fasting plasma glucose (FPG₁st ) and HbA₁c were assayed in each participant. Diabetic candidates with FPG₁st ≥ 5·6 mmol/l or HbA₁c ≥ 39 mmol/mol (5·7%) were informed to undergo a 75-g oral glucose tolerance test (OGTT). Diagnosis of diabetes was made by 1999 World Health Organization criteria. Sensitivity and specificity of HbA1 c for diagnosing diabetes were calculated by receiver operating characteristics (ROC) curve.
  
  
  RESULTS
  Among 1494 subjects, 161 subjects (10·8%) with previously diagnosed diabetes and 21 with missing data were excluded. Among the remaining 1312 subjects (87·8%), 861 subjects (65·6%) with either FPG1st ≥ 5·6 mmol/l or HbA₁c ≥ 39 mmol/mol (5·7%) were invited to perform OGTT. Finally, 453 subjects (52·6%) performed OGTT (FPG₂nd and 2-h plasma glucose were measured) and 54 subjects (11·9%) were identified as being diabetes. The area under ROC curve was 0·916 (0·887-0·940) for HbA₁c and 0·972 (0·953-0·985) for FPG₂nd in diagnosing diabetes (P = 0·045). An HbA₁c threshold of 48 mmol/mol (6·5%) yielded the highest combination of sensitivity (75·9%) and specificity (95·5%) for diagnosing diabetes.
  
  
  CONCLUSIONS
  An HbA1 c threshold of 48 mmol/mol (6·5%) was highly specific and had a good sensitivity for diagnosing diabetes among Chinese subjects aged over 50 years with FPG ≥ 5·6 mmol/l or HbA₁c ≥ 39 mmol/mol (5·7%). This threshold may be suitable for diagnosing diabetes in Chinese subjects over 50 years old.
authors.affiliation: Department of Endocrinology, The 3rd Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Lin
authors.forename: Li
authors.initials: L
authors.lastname: Hu
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Li
authors.forename: Yanming
authors.initials: Y
authors.lastname: Chen
authors.forename: Haixia
authors.initials: H
authors.lastname: Xu
authors.forename: Shengqing
authors.initials: S
authors.lastname: He
authors.forename: Zhuozhuo
authors.initials: Z
authors.lastname: Ren
authors.forename: Xixiang
authors.initials: X
authors.lastname: Tang
authors.forename: Yawei
authors.initials: Y
authors.lastname: Qiu
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Panwei
authors.initials: P
authors.lastname: Mu
authors.forename: Longyi
authors.initials: L
authors.lastname: Zeng
mesh_terms: D000367:Age Factors; D000368:Aged; D001786:Blood Glucose / Q000032:analysis; D002681:China; D003153:Community Health Services; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000097:blood / Q000175:diagnosis*; D005260:Female; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin