title: Haemoglobin A1c cut-off point to identify a high risk group of future diabetes: results from the Omiya MA Cohort Study.
abstract: OBJECTIVE
  Using the HbA(1c) level to define diabetes has several advantages and these advantages also apply to define a high-risk group. However, the risk of diabetes increases as HbA(1c) increases and a certain degree of arbitrariness in the cut-off for the high risk group is unavoidable. The aim of this study was to determine the HbA(1c) cut-off for defining a high-risk group that corresponds to the fasting plasma glucose cut-off by comparing the risk of diabetes against the fasting plasma glucose and HbA(1c) levels in the Japanese population.
  
  
  METHODS
  A retrospective cohort study was conducted using data from annual health examinations performed in Omiya city. A total of 11,271 subjects between the ages of 40 and 79 years without diabetes at baseline were followed for up to 7 years. According to the new diagnostic criteria, diabetes was defined as an fasting plasma glucose level ≥ 7 mmol/l or an HbA(1c) level ≥ 48 mmol/mol (≥ 6.5%) or a self-report. The HbA(1c) cut-off corresponding to the fasting plasma glucose cut-off was determined using the incidence, hazard ratio, and a receiver operating characteristic analysis.
  
  
  RESULTS
  Eight hundred and sixty subjects developed diabetes. The incidence, hazard ratio, and receiver operating characteristic analysis all indicated that an HbA(1c) cut-off of 39 mmol/mol (5.7%) corresponded to an fasting plasma glucose level of 5.6 mmol/l.
  
  
  CONCLUSIONS
  Our results suggested that the HbA(1c) cut-off for high-risk of diabetes should be 39 mmol/mol (5.7%), consistent with the American Diabetes Association recommendation. Further research is needed to determine whether our results are applicable to other populations.
authors.affiliation: Japan Foundation for Promotion of International Medical Research Cooperation, Saitama, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kato
authors.forename: M
authors.initials: M
authors.lastname: Noda
authors.forename: H
authors.initials: H
authors.lastname: Suga
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: M
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Y
authors.initials: Y
authors.lastname: Kanazawa
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D044466:Asian People; D001786:Blood Glucose / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology; D005215:Fasting / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human