Objective: We sought to report the 6-year incidence of proteinuria and associated risk factors in African Americans with type 1 diabetes.
Research design and methods: African Americans (n = 483) with type 1 diabetes were reexamined in a 6-year follow-up study. Proteinuria and creatinuria were measured in 4-h timed urine specimens obtained at initial and follow-up visits. Other evaluations included a structured clinical interview, ocular examination, masked grading of seven stereoscopic fundus photographs, blood pressure measurements, blood assays, and administration of the Beck Depression Inventory (BDI).
Results: Over the 6-year period, 117 (42.9%) of the 473 patients at risk developed "any" proteinuria, defined as either microalbuminuria (26.0%) or overt (16.9%) proteinuria; 87 (23.5%) progressed from micro- or no albuminuria to overt proteinuria and 39 (8.7%) to end-stage renal disease; and 40 (20.6%) regressed. Peak incidence of any proteinuria occurred for patients who were 10-14 years of age or had 5-10 years of diabetes duration at baseline. Multiple regression analysis showed that baseline albumin excretion rate (AER), systemic hypertension, blood cholesterol, and high BDI depression scores were significant and independent risk factors for incidence of any proteinuria.
Conclusions: In African Americans with type 1 diabetes, the 6-year incidence of proteinuria is high, particularly among young patients and those with a relatively short duration of diabetes at baseline. Baseline AER is the strongest predictor for incidence of any proteinuria.