Racial differences in the relationship between blood pressure and risk of retinopathy among individuals with NIDDM

OBJECTIVE - To assess whether the prevalence of retinopathy differs between blacks and whites with diabetes and to examine differences between blacks and whites in the relationship between risk factors for and prevalence of retinopathy. Population data suggest diabetic retinopathy is either more prevalent or more severe in blacks than in whites. RESEARCH DESIGN AND METHODS - We analyzed data from a screening study for retinopathy among patients with diabetes, conducted in Maryland from 1986-1990. RESULTS - After adjusting for age, duration of diabetes, type of treatment for diabetes, and presence or absence of high blood pressure, black men with NIDDM were ∼23% more likely to have retinopathy than other race-sex groups (not statistically significant). We also found a different relationship between systolic blood pressure and retinopathy prevalence in blacks than in whites among individuals with NIDDM. Among blacks, the risk increased as systolic blood pressure increased, even within the normal range, and reached statistical significance at > 150 mmHg. Among whites, the risk was increased only among those with high systolic blood pressure (>140 mmHg) and did not reach statistical significance. CONCLUSIONS - Our data are consistent with the hypothesis that differences exist between blacks and whites in risk of diabetic retinopathy, and that the effect of blood pressure on risk of retinopathy differs between blacks and whites.