COMMENTS AND RESPONSES Hemoglobin A1c Diagnostic Cutoff Differences Between Black

through 2008, Tsugawa and colleagues (1) report a retinopathy prev-alence of 6.3 % for white persons and 13.1 % for black persons. Using as a reference category a control group with hemoglobin A1c (HbA1c) levels less than 5.5%, the authors state that white persons showed a significantly greater adjusted prevalence of retinopathy at HbA1c lev-els of 6.0 % to 6.4 % or higher compared with 5.5 % to 5.9 % for black persons. This report that black persons develop “diabetic retinopathy ” at lower HbA1c levels (and presumably lower glycemic burden) than white persons suggests a leftward shift in the retinal toxicity curve for glycemic burden in black persons compared with white persons. Among black persons with diabetes, the higher relative risk for reti-nopathy compared with white persons may be attributed to dispari-ties in glycemic control, because it is abrogated by improved access to care (2)