ETHNIC DISPARITY IN HEMOGLOBIN A1c LEVELS AMONG NORMOGLYCEMIC OFFSPRING OF PARENTS WITH TYPE 2 DIABETES MELLITUS

Objective: To investigate the racial/ethnic disparities in hemoglobin A(1c) levels among nondiabetic persons with similar parental history of type 2 diabetes mellitus. Methods: We studied a community-based sample of adult offspring of parents with type 2 diabetes mellitus. Measurements included anthropometry, hematology assessments, serial fasting plasma glucose, oral glucose tolerance testing, plasma insulin, hemoglobin A(1c), insulin sensitivity, and beta-cell function, using a homeostasis model assessment. Results: The study included 302 participants (135 white, 167 black). Compared with white participants, black participants had lower fasting plasma glucose levels (91.9 +/- 0.51 mg/dL vs 93.6 +/- 0.50 mg/dL, P = .015), lower area under the curve of plasma glucose during oral glucose tolerance testing (P = <.001), higher body mass index (31.1 +/- 0.61 kg/m(2) vs 28.5 +/- 0.57 kg/m2, P = <.001), and similar insulin sensitivity and beta-cell function. Hemoglobin A(1c) was higher in black participants than in white participants (5.68 +/- 0.033% vs 5.45 +/- 0.028%, P<.001). The absolute black-white difference in hemoglobin A(1c) level of approximately 0.22% persisted after adjusting for age, hemoglobin, hematocrit, body mass index, waist circumference, fasting plasma glucose, glucose area under the curve, and other covariates. Conclusions: Among healthy offspring of parents with type 2 diabetes mellitus in this study, African American participants had higher hemoglobin A(1c) levels than white participants after adjusting for age, adiposity, blood glucose, and known variables. Thus, plasma glucose level is more valid than hemoglobin A(1c) for diagnosing prediabetes or diabetes in black persons. (Endocr Pract. 2012; 18:356-362)