Differences in Glycosylated Hemoglobin — Independent of Glucose Levels — Between Blacks and Whites

The concentration of serum glucose is highly correlated with the glycosylated hemoglobin (HbA_1c) level; however, factors such as race, genetics, and physiology also can influence HbA_1c levels. In this study, which involved more than 3000 U.S. residents, researchers evaluated whether black–white differences in HbA_1c levels persisted after controlling for glucose level. Data (including HbA_1c levels and oral glucose tolerance results) were from the Screening for Impaired Glucose Tolerance and the NHANES III trials.

After researchers adjusted for fasting and 2-hour glucose tolerance results, black subjects had higher HbA_1c levels than did whites. The absolute difference correlated with serum glucose levels: Values among blacks were 0.13% higher …