title: HbA1c of 6.5% to diagnose diabetes mellitus -- does it work for us? -- the Bellville South Africa study.
abstract: BACKGROUND
  HbA1c has been the gold standard for glycaemic control follow-up for decades. In 2009, a level of 6.5% (48 mmol/mol) was proposed as diagnostic for diabetes. We test this cut-off in our community.
  
  
  METHODS
  Participants (946) from a community-based study were screened for diabetes using either a fasting blood glucose or oral glucose tolerance test (OFTT). The HbA1c cut-off of 6.5% was tested for each group. A receiver operator characteristic (ROC) curve for both groups was generated to establish an optimal cut-off.
  
  
  RESULTS
  Our study included 224 (23.7%) males and 722 (76.3%) females. Using fasting blood glucose alone, 117 (14%) were diagnosed with diabetes--50% had an HbA1c value of ≥6.5% (48 mmol/mol). Using an OGTT, 147 (18%) were diagnosed with diabetes--46% had an HbA1c value of ≥6.5% (48 mmol/mol). ROC curves found a level of 6.1% (43 mmol/mol) to be optimal in both groups (AUC 0.85 and 0.82 respectively). The sensitivities were 80% and 75% and the specificities 77% and 78% respectively.
  
  
  CONCLUSIONS
  A cut off of 6.5% (48 mmol/mol) is a good diagnostic tool with its high specificity; however the low sensitivity limits its use. We found a level of 6.1% (43 mmol/mol) to be optimal. This emphasizes the need for evidenced based values to be established in various population groups.
authors.affiliation: Division of Chemical Pathology, Faculty of Health Sciences, National Health Laboratory Service and University of Stellenbosch, Cape Town, South Africa.
authors.forename: Annalise E
authors.initials: AE
authors.lastname: Zemlin
authors.forename: Tandi E
authors.initials: TE
authors.lastname: Matsha
authors.forename: Mogamat S
authors.initials: MS
authors.lastname: Hassan
authors.forename: Rajiv T
authors.initials: RT
authors.lastname: Erasmus
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose / Q000378:metabolism*; D003920:Diabetes Mellitus / Q000097:blood* / Q000175:diagnosis*; D005215:Fasting / Q000097:blood; D005260:Female; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D013019:South Africa; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin