Is gross proteinuria a risk factor for the incidence of proliferative diabetic retinopathy?

To examine the relationship between gross proteinuria, measured at the initial examination, and the 4-year incidence of proliferative diabetic retinopathy (PDR) in a population-based study in Wisconsin.

Gross proteinuria was measured by reagent strip. Diabetic retinopathy was determined from stereoscopic fundus photographs in a masked fashion using the modified Airlie House classification scheme.

In the younger-onset group taking insulin (n = 693), the relative risk of proliferative retinopathy developing in those with gross proteinuria at baseline was 2.32 (95% confidence interval [CI]: 1.40,3.83) compared with those without gross proteinuria. For the older-onset group taking insulin, the relative risk was 2.02 (95% CI: 0.91,4.44), and for those not taking insulin it was 1.13 (95% CI: 0.15,8.50). After controlling for other risk variables, the relationship was of borderline statistical significance (P = 0.052) in the younger-onset group with no or early nonproliferative retinopathy at baseline.

These data suggest that gross proteinuria is a risk indicator for proliferative retinopathy in younger-onset patients with diabetes. These patients might benefit from having regular ophthalmologic evaluation.