Retinopathy in African Americans and whites with insulin-dependent diabetes mellitus

The development and progression of diabetic retinopathy in African Americans with insulin-dependent diabetes mellitus is not known.

Two hundred subjects with insulin-dependent diabetes mellitus with duration of diabetes 16 years or less at first visit were studied; 58 were African Americans and 142 were whites. All had gradable stereoscopic color fundus photographs (seven standard fields) from at least two visits (mean time between first and second visit was 4.1 years). Subjects with hemoglobinopathy or proliferative retinopathy or subjects who had evidence of treatment for proliferative retinopathy at first visit were excluded. Masked grading of photographs was conducted using the modified Airlie House classification scheme.

African Americans were older, heavier, had higher systolic blood pressure (all P < .05), and marginally higher hemoglobin A1 (HbA1) values (P = .06) than the whites at first visit. African Americans had a lower rate of two steps or more progression from preexistent retinopathy (19%) than whites (43%). Progression to proliferative retinopathy or treatment was similar by race. Multivariate analysis predicting development oe progression of retinopathy, while controlling for length of follow-up, found higher HbA1 (odds ratio [OR] = 2.15), longer duration of insulin-dependent diabetes mellitus (OR = 1.69), higher serum creatinine concentration (OR = 1.59), and white race (OR = 2.62) to be independent risk factors.

These data suggest a previously unsuspected reduction in the adjusted risk for development and progression of retinopathy in African Americans. The reason for this apparently reduced risk are not known.