title: Optimal range of HbA1c for the prediction of future diabetes: a 4-year longitudinal study.
abstract: OBJECTIVE
  A glycated hemoglobin (HbA1c) range of 5.7-6.4% has been included as a category of increased risk for diabetes. We evaluated whether or not it is reasonable to apply this HbA1c range to Koreans.
  
  
  METHODS
  A retrospective analysis was conducted among subjects who participated in comprehensive health check-ups annually for 5 years. A total of 9723 subjects were classified into 12 categories based on the baseline HbA1c level.
  
  
  RESULTS
  During 4 years, 601 of the 9723 subjects (6.2%) developed diabetes. Based on ROC analysis, a HbA1c of 5.7% gave an optimal sensitivity of 62% and specificity of 85% to predict diabetes. The point showing a substantial difference in the Kaplan-Meier curves was a HbA1c of 5.7%. The incidence of diabetes was 20.8% among subjects with a baseline HbA1c of 5.7-6.4%. The hazard ratio of developing diabetes was 6.5 (95% CI, 3.7-10.2) in the subjects with a HbA1c of 5.7% compared with the bottom category of HbA1c (<5.0%).
  
  
  CONCLUSIONS
  A HbA1c cut-point of 5.7% is a suitable value for predicting future diabetes. It is reasonable to consider a HbA1c range of 5.7-6.4% as a category of increased risk for diabetes in Korean, similar to an IFG or IGT.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Ji Cheol
authors.initials: JC
authors.lastname: Bae
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Rhee
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address: drlwy@hanmail.net.
authors.forename: Won Young
authors.initials: WY
authors.lastname: Lee
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Se Eun
authors.initials: SE
authors.lastname: Park
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Cheol Young
authors.initials: CY
authors.lastname: Park
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Ki Won
authors.initials: KW
authors.lastname: Oh
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Sung Woo
authors.initials: SW
authors.lastname: Park
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Sun Woo
authors.initials: SW
authors.lastname: Kim
mesh_terms: D000328:Adult; D003920:Diabetes Mellitus / Q000175:diagnosis* / Q000208:ethnology; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis* / Q000592:standards; D006801:Humans; D007723:Korea; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011236:Prediabetic State / Q000175:diagnosis; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012306:Risk; D012680:Sensitivity and Specificity
chemical_list: D006442:Glycated Hemoglobin