Is race related to glycemic control? An assessment of glycosylated hemoglobin in two South Carolina communities.

To consider the relationship between race and long-term glycemic control, as measured by glycosylated hemoglobin (GHb), we analyzed data from a community-based sample of 3175 adults in the South Carolina Cardiovascular Disease Prevention Project. A clinically meaningful difference for mean GHb levels (10.5 vs 8.4%, P < 0.001) was present between black people and white people reporting diabetes. Similarly, a significant association between race and GHb was present among people reporting "borderline diabetes" or no diabetes. Logistic regression confirmed this finding in all three diabetic categories, however, controlling for insulin use in the diabetic group reduced (P < 0.001) the association between GHb and race. These findings confirm that further improvements in glycemic control are necessary, especially for black patients and that black people not reporting diabetes have higher GHb levels compared to white people, possibly due to undiagnosed diabetes.