BACKGROUND: Hemoglobin A1c (HbA1c) levels are known to be consistently higher in black persons than in white persons at any given glycemic level. Whether the optimal diagnostic threshold of HbA1c should differ between blacks and whites is unclear. OBJECTIVE: To compare the relationships between HbA1c level and the prevalence of retinopathy in black and white U.S. adults. DESIGN: Cross-sectional study. SETTING: A nationally representative sample of the National Health and Nutrition Examination Survey from 2005 through 2008. PATIENTS: 2804 white persons and 1008 black persons aged 40 years or older in the United States. MEASUREMENTS: Prevalence of retinopathy. Logistic regression models and restricted cubic spline models were constructed separately for white and black populations to test the HbA1c levels at which risk for retinopathy begins to increase. RESULTS: After adjustment for age, sex, hypertension, body mass index, family history of diabetes, and use of antidiabetes medications or insulin, the lowest HbA1c category for which the prevalence of retinopathy was significantly higher than the reference category (<5.5%) was 6.0% to 6.4% for white persons (risk difference, 4.8% [95% CI, 0.5% to 9.1%]) and 5.5% to 5.9% for black persons (risk difference, 5.3% [CI, 1.0% to 9.5%]). The restricted cubic spline models indicated that the risk for retinopathy increased at lower HbA1c levels in black persons than in white persons. LIMITATION: The cross-sectional design of the study precluded examining the effect of the duration at each HbA1c level. CONCLUSION: The prevalence of retinopathy begins to increase at a lower HbA1c level in black Americans than in white Americans. The findings do not support increasing the diagnostic threshold of HbA1c in black persons. PRIMARY FUNDING SOURCE: None.
BACKGROUND: Hemoglobin A1c (HbA1c) levels are known to be consistently higher in black persons than in white persons at any given glycemic level. Whether the optimal diagnostic threshold of HbA1c should differ between blacks and whites is unclear. OBJECTIVE: To compare the relationships between HbA1c level and the prevalence of retinopathy in black and white U.S. adults. DESIGN: Cross-sectional study. SETTING: A nationally representative sample of the National Health and Nutrition Examination Survey from 2005 through 2008. PATIENTS: 2804 white persons and 1008 black persons aged 40 years or older in the United States. MEASUREMENTS: Prevalence of retinopathy. Logistic regression models and restricted cubic spline models were constructed separately for white and black populations to test the HbA1c levels at which risk for retinopathy begins to increase. RESULTS: After adjustment for age, sex, hypertension, body mass index, family history of diabetes, and use of antidiabetes medications or insulin, the lowest HbA1c category for which the prevalence of retinopathy was significantly higher than the reference category (<5.5%) was 6.0% to 6.4% for white persons (risk difference, 4.8% [95% CI, 0.5% to 9.1%]) and 5.5% to 5.9% for black persons (risk difference, 5.3% [CI, 1.0% to 9.5%]). The restricted cubic spline models indicated that the risk for retinopathy increased at lower HbA1c levels in black persons than in white persons. LIMITATION: The cross-sectional design of the study precluded examining the effect of the duration at each HbA1c level. CONCLUSION: The prevalence of retinopathy begins to increase at a lower HbA1c level in black Americans than in white Americans. The findings do not support increasing the diagnostic threshold of HbA1c in black persons. PRIMARY FUNDING SOURCE: None.
Authors: Jinan B Saaddine; Anne Fagot-Campagna; Deborah Rolka; K M Venkat Narayan; Linda Geiss; Mark Eberhardt; Katherine M Flegal Journal: Diabetes Care Date: 2002-08 Impact factor: 19.112
Authors: Christina M Parrinello; A Richey Sharrett; Nisa M Maruthur; Richard M Bergenstal; Morgan E Grams; Josef Coresh; Elizabeth Selvin Journal: Diabetes Care Date: 2015-12-17 Impact factor: 19.112
Authors: Keith C Ferdinand; Fatima Rodriguez; Samar A Nasser; A Enrique Caballero; Gary A Puckrein; Farhad Zangeneh; Michael Mansour; JoAnne Micale Foody; Priscilla E Pemu; Elizabeth O Ofili Journal: Cardiorenal Med Date: 2013-12-31 Impact factor: 2.041
Authors: David S Goldberg; Karen Krok; Sachin Batra; James F Trotter; Steven M Kawut; Michael B Fallon Journal: Gastroenterology Date: 2014-01-08 Impact factor: 22.682