HbA1c Levels Found Higher in Blacks Than Whites

TUESDAY, June 15 (HealthDay News) -- Black individuals have higher hemoglobin A1c levels than whites across the spectrum from normal glucose tolerance to diabetes, and as glucose intolerance worsens, the differences become greater, according to research published in the June 15 issue of the Annals of Internal Medicine.

David C. Ziemer, M.D., of Emory University in Atlanta, and colleagues analyzed data from two groups -- 1,581 non-Hispanic blacks and whites ages 18 to 87 in the Screening for Impaired Glucose Tolerance (SIGT) study, and 1,967 who were older than 40 in the Third National Health and Nutrition Examination Survey (NHANES III). None had a previous diabetes diagnosis.

The researchers found that hemoglobin A1c levels in participants with normal glucose tolerance were higher in blacks than whites (0.13 percentage points in the SIGT group and 0.21 in the NHANES III group). Among those with pre-diabetes or diabetes, hemoglobin A1c was also higher in blacks: for pre-diabetes, the differences were 0.26 and 0.30 percentage points, respectively, in the two groups, and in those with diabetes, the difference was 0.47 in both groups. These values were found after adjusting for plasma glucose levels and other factors linked to hemoglobin A1c.

The authors "highlight the limitations inherent in any new measure of average glycemia and the need to characterize the sources and effect of the variation. In light of observed variation, clinicians should consider the potential peril of the American Diabetes Association's recommendation to dichotomize hemoglobin A1c levels for diagnosis (<6.5 percent [nondiabetic] versus ≥6.5 percent [diabetic])," write the authors of an accompanying editorial.

Abstract
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