Abstract 015: No Racial Differences in the Association of Glycated Hemoglobin with Kidney Disease and Cardiovascular Outcomes
Background: There is debate regarding the clinical significance of racial differences in glycated hemoglobin (HbA1c) and their implications for diagnosis of diabetes. Studies demonstrating higher HbA1c values in ethnic minority populations as compared to whites have led to questions regarding the use and interpretation of HbA1c in racial minorities.
Methods: We conducted a prospective cohort analysis of participants without diabetes or cardiovascular disease at baseline from the community-based ARIC 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 incident kidney disease, cardiovascular outcomes, and mortality in black and white participants and tested for interactions by race in multivariable Cox proportional hazards models.
Findings: Baseline characteristics differed significantly in blacks vs 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 non-fatal coronary heart disease, total stroke, and ischemic stroke across categories of HbA1c in both blacks and whites. The adjusted hazard ratios (HRs) for the race-interactions are shown in the Figure. The adjusted HRs for categories of HbA1c were similar in blacks and whites for each outcome (all p-for-interaction >0.05) except for all-cause mortality. Patterns of association were similar, but weaker, for fasting glucose. HbA1c and fasting glucose were both more strongly associated with all-cause mortality in whites compared to blacks, largely explained by competing mortality.
Interpretation: HbA1c is an important risk factor for vascular outcomes and mortality in both black and white middle-aged 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 test results in blacks and whites for diagnosis and treatment of diabetes mellitus.
- © 2013 by American Heart Association, Inc.