title: Ethnic variation in the correlation between random serum glucose concentration and glycated haemoglobin.
abstract: OBJECTIVE
  To determine if the relationship between serum glucose concentration and glycated haemoglobin is different between African-Americans and whites.
  
  
  METHODS
  Retrospective cross-sectional study comparing the association between glycated haemoglobin and serum glucose levels, based upon ethnicity. Two databases were evaluated: (i) 4215 African-American and 6359 white outpatients who had simultaneous glycated haemoglobin, random serum glucose and creatinine concentration measurements between 2000 and 2007 at the North Carolina Baptist Hospital and (ii) 1021 white and 312 African-American Diabetes Heart Study (DHS) participants.
  
  
  RESULTS
  In North Carolina Baptist Hospital clinic attendees, a given glycated haemoglobin was associated with higher serum glucose concentrations in African-Americans compared with whites. In a multivariate model with glycated haemoglobin as the outcome variable, racial differences remained significant after adjustment for serum glucose, age, gender and kidney function. For individuals with a serum glucose between 5.6 and 8.3 mmol/l, the glucose : glycated haemoglobin ratio was 1.03 +/- 0.16 mmol/l/% in white individuals and 0.99 +/- 0.17 mmol/l/% in African-Americans (P < 0.0001). For a glycated haemoglobin value of 7.0%, there was a 0.98-mmol/l difference in predicted serum glucose concentration in 50-year-old African-American men, relative to white. Results were replicated in the DHS, where in a best-fit linear model, after adjustment for glucose, African-American race was a significant predictor of glycated haemoglobin (P < 0.0001).
  
  
  CONCLUSIONS
  African-Americans have higher glycated haemoglobin values at given serum glucose concentrations relative to whites. This finding may contribute to the observed difference in glycated haemoglobin values reported between these race groups.
authors.affiliation: Section on Nephrology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA. ableyer@wfubmc.edu
authors.forename: A J
authors.initials: AJ
authors.lastname: Bleyer
authors.forename: D
authors.initials: D
authors.lastname: Hire
authors.forename: G B
authors.initials: GB
authors.lastname: Russell
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: J
authors.initials: J
authors.lastname: Divers
authors.forename: Z
authors.initials: Z
authors.lastname: Shihabi
authors.forename: D W
authors.initials: DW
authors.lastname: Bowden
authors.forename: B I
authors.initials: BI
authors.lastname: Freedman
mesh_terms: D000328:Adult; D001741:Black or African American; D000368:Aged; D001786:Blood Glucose / Q000032:analysis*; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009657:North Carolina; D012189:Retrospective Studies; D044465:White People
chemical_list: D001786:Blood Glucose; D003404:Creatinine; D006442:Glycated Hemoglobin