title: No racial differences in the association of glycated hemoglobin with kidney disease and cardiovascular outcomes.
abstract: OBJECTIVE
  There is debate regarding the clinical significance of well-established racial differences in HbA1c. We compared the associations of diabetes diagnostic categories for HbA1c and fasting glucose with clinical outcomes in black and white persons in the community.
  
  
  METHODS
  We conducted a prospective cohort analysis of participants without diabetes or cardiovascular disease from the Atherosclerosis Risk in Communities study. We examined the associations of clinical categories of HbA1c (<5.7%, 5.7-6.4%, ≥6.5%) and fasting glucose (<100, 100-125, ≥126 mg/dL) with outcomes separately among 2,484 black and 8,593 white participants and tested for race interactions.
  
  
  RESULTS
  Baseline characteristics differed significantly in blacks compared with whites, including HbA1c (5.8 vs. 5.4%; P<0.001). During 18 years of follow-up, there were trends of increased risk of kidney disease, fatal and nonfatal coronary heart disease, and stroke across categories of HbA1c in both blacks and whites. The adjusted hazard ratios for each outcome across categories of HbA1c were similar in blacks and whites (P for interaction>0.05) except for all-cause mortality. Patterns of association were similar, but weaker, for fasting glucose. HbA1c and fasting glucose both were more strongly associated with all-cause mortality in whites compared with blacks, largely explained by racial differences in the rate of cardiovascular deaths.
  
  
  CONCLUSIONS
  HbA1c is a risk factor for vascular outcomes and mortality in both black and white adults. Patterns of association for HbA1c were similar to or stronger than those for fasting glucose. With respect to long-term outcomes, our findings support a similar interpretation of HbA1c in blacks and whites for diagnosis and treatment of diabetes mellitus.
authors.affiliation: Corresponding author: Elizabeth Selvin, lselvin@jhsph.edu.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Selvin
authors.forename: Andreea M
authors.initials: AM
authors.lastname: Rawlings
authors.forename: Richard M
authors.initials: RM
authors.lastname: Bergenstal
authors.forename: Josef
authors.initials: J
authors.lastname: Coresh
authors.forename: Frederick L
authors.initials: FL
authors.lastname: Brancati
mesh_terms: D044383:Black People / Q000706:statistics & numerical data; D003327:Coronary Disease / Q000453:epidemiology* / Q000378:metabolism* / Q000401:mortality; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D007674:Kidney Diseases / Q000453:epidemiology* / Q000378:metabolism* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D044465:White People / Q000706:statistics & numerical data
chemical_list: D006442:Glycated Hemoglobin