Prevalence of major type 1 diabetes complications and risk factors in whites and blacks in the national health and nutrition examination survey (NHANES 1999-2008): Is race a risk factor?

Background: Mortality for non-Hispanic blacks (NHBs) with type 1 diabetes (T1D) is nearly 2.5 times higher than non-Hispanic whites (NHWs) and the factors contributing to this disparity remain unclear. The objectives of this study were to compare the prevalence of T1D complications between NHWs and NHBs in a nationally representative sample and to evaluate the impact of modifiable risk factors and race on these outcomes. Methods: Individuals with T1D were identified in the NHANES 1999-2008 as individuals diagnosed with diabetes less than age 30 and on continuous insulin therapy. Complication and risk factor status were determined based on self-reported questionnaire responses and relevant laboratory components. Results: The prevalence of CVD did not differ by race, and race was not associated with CVD after adjusting for risk factors. The prevalence of nephropathy (NHBs: 48.6%; NHWs: 18.4%, p<.01) and retinopathy (NHBs: 83.1%; NHWs: 43.4%, p=.01) at >20 years duration was significantly higher in NHBs. Race was significantly associated with nephropathy [OR (95%CI): 1.30 (1.11, 1.54)] and retinopathy [OR (95%CI): 1.39 (1.14, 1.70)] after adjusting for clinical and demographic risk factors. Conclusions: These data suggest that NHBs with T1D are at increased risk of developing nephropathy and retinopathy, independent of well-established risk factors for these complications. This disparity may be associated with access to care, non-traditional risk factors, or genetic susceptibility.