title: Do glycemic marker levels vary by race? Differing results from a cross-sectional analysis of individuals with and without diagnosed diabetes.
abstract: OBJECTIVE
  It is well known that A1c varies by race. However, racial differences in other biomarkers of hyperglycemia are less well characterized. The objective of this study was to determine whether average levels of glycemic markers differ by race in adults with and without diagnosed diabetes, before and after accounting for postchallenge glucose.
  
  
  METHODS
  This cross-sectional study included 2692 middle-aged men and women (5.5% with diagnosed diabetes; 44% African-American; and 56% white) from the Coronary Artery Risk Development in Young Adults Study (2005-2006) who had fasting glucose, 2-hour postchallenge glucose, A1c, glycated albumin, fructosamine, and 1,5-anhydroglucitol (1,5-AG) measured. Multiple linear regression was used to evaluate racial differences in mean levels of each glycemic marker stratified by the diabetes status and adjusted for sociodemographics, cardiovascular factors, and postchallenge glucose.
  
  
  RESULTS
  Among those with diagnosed diabetes, racial differences were not observed for any of the glycemic markers. In contrast, among those without diagnosed diabetes, African-Americans had higher mean levels than whites of A1c (β=0.19% points; 95% CI 0.14 to 0.24), glycated albumin (β=0.82% points; 95% CI 0.68 to 0.97), fructosamine (β=8.68 μmol/L; 95% CI 6.68 to 10.68), and 2-hour glucose (β=3.50 mg/dL; 95% CI 0.10 to 6.90) after multivariable adjustment, whereas there were no statistically significant racial difference in 1,5-AG. The racial differences observed for A1c, glycated albumin, and fructosamine persisted after further adjustment for fasting and 2-hour glucose and were of similar magnitude (SD units).
  
  
  CONCLUSIONS
  Racial differences in glycemic marker levels were evident among middle-aged adults without diagnosed diabetes even after adjustment for postchallenge glucose. Whether these racial differences in biomarkers of hyperglycemia affect the risk of complications warrants additional study.
authors.affiliation: Department of Epidemiology , University of Alabama at Birmingham School of Public Health , Birmingham, Alabama , USA.
authors.forename: April P
authors.initials: AP
authors.lastname: Carson
authors.affiliation: Department of Epidemiology , University of Alabama at Birmingham School of Public Health , Birmingham, Alabama , USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Muntner
authors.affiliation: Department of Epidemiology , Johns Hopkins University Bloomberg School of Public Health , Baltimore, Maryland , USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Selvin
authors.affiliation: Department of Preventive Medicine , Northwestern University Feinberg School of Medicine , Chicago, Illinois , USA.
authors.forename: Mercedes R
authors.initials: MR
authors.lastname: Carnethon
authors.affiliation: Division of Preventive Medicine , University of Alabama at Birmingham School of Medicine , Birmingham, Alabama , USA.
authors.forename: Xuelin
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Laboratory Medicine and Pathology , University of Minnesota Medical School , Minneapolis, Minnesota , USA.
authors.forename: Myron D
authors.initials: MD
authors.lastname: Gross
authors.affiliation: Department of Nutrition Sciences, University of Alabama at Birmingham School of Health Professions, Birmingham, Alabama, USA; Birmingham VA Medical Center, Birmingham, Alabama, USA.
authors.forename: W Timothy
authors.initials: WT
authors.lastname: Garvey
authors.affiliation: Division of Preventive Medicine , University of Alabama at Birmingham School of Medicine , Birmingham, Alabama , USA.
authors.forename: Cora E
authors.initials: CE
authors.lastname: Lewis
keywords: Fructosamine; Glycemia; Hemoglobin A1c; Race