The National Health and Nutrition Examination Survey 2005–2008

OBJECTIVEdCurrent recommendations for the use of hemoglobin A1c (HbA1c) in diabetes screening and diagnosis aim to identify those at greatest risk for diabetic microvascular compli-cations. However, there is current controversy regarding the clinical implications of ethnic differ-ences in HbA1c values. The objective of this study was to determine whether the association between HbA1c and retinopathy differs by ethnic group in a representative sample of U.S. adults. RESEARCH DESIGN AND METHODSdThe study was a cross-sectional analysis of 2,945 non-Hispanic white, 1,046 non-Hispanic black, and 1,231 Hispanic American partici-pants aged$40 years from the 2005–2008 National Health and Nutrition Examination Survey. RESULTSdAmong nondiabetic adults, the mean HbA1c was 5.5 % in non-Hispanic whites, 5.7 % in non-Hispanic blacks, and 5.6 % in Hispanic Americans. Among those with diagnosed diabetes, mean HbA1c was 6.9 % in non-Hispanic whites, 7.5 % in non-Hispanic Blacks, and 7.7 % in Hispanic Americans. Overall, non-Hispanic blacks had the highest prevalence of reti-nopathy. In multivariable logistic models, HbA1c clinical categories were strongly associated with prevalent retinopathy. However, the magnitude of the association did not differ by ethnic group (all P values for interaction $ 0.7). Similar results were observed with HbA1c modele