Racial differences in glycemic markers: A cross-sectional analysis of community-based data

Background: Although differences between black and white persons in hemoglobin A_1c (HbA_1c) values are well established, recent studies suggest that this might not reflect differences in glycemia. Objective: To investigate racial disparities in glycemic markers, including those that reflect biological processes independent of hemoglobin glycation and erythrocyte turnover. Design: Cross-sectional. Setting: Community-based. Participants: 1376 nondiabetic and 343 diabetic adults in a substudy of the Atherosclerosis Risk in Communities Study. Measurements: Hemoglobin A_1c, fasting glucose, glycated albumin, fructosamine, and 1,5-anhydroglucitol levels. Results: Among persons with and without diabetes, black persons had significantly higher HbA_1c, glycated albumin, and fructosamine levels than white persons before and after adjustment for covariates and fasting glucose concentration. Serum 1,5-anhydroglucitol levels, which are reduced in the setting of hyperglycemia-induced glycosuria, were lower in black persons than in white persons, although this difference was statistically significant only in nondiabetic adults. Limitation: The design was cross-sectional, a limited number of participants with a history of diabetes was included, and the study did not include integrated measures of circulating nonfasting glycemia. Conclusion: Differences between black and white persons in glycated albumin, fructosamine, and 1,5-anhydroglucitol levels parallel differences between these groups in HbA_1c values. Racial differences in hemoglobin glycation and erythrocyte turnover cannot explain racial disparities in these serum markers. The possibility that black persons have systematically higher levels of nonfasting glycemia warrants further study. Primary Funding Source: National institutes of health, National institute of diabetes and digestive and kidney diseases.