Prospective study of development of microalbuminuria and retinopathy in Brazilian IDDM patients

With the aim to study potential risk factors for the development of microalbuminuria and retinopathy, baseline characteristics were examined in 50 Brazilian IDDM patients followed for 4.48 years with a 2-year reexamination. During the study, 3 patients (6%) aged 25.9 +/- 4.4 years, duration of diabetes 8.1 +/- 4.2 years, died from acute complications without microalbuminuria and retinopathy after a follow-up of 2.1 +/- 0.7 years. The standardized mortality rate for the group was 0.84 per 1000 (95% CL, 0.31, 1.83) in comparison to 0.14 per 1000 in the general population. From 34 normoalbuminuric individuals at baseline (urinary albumin excretion rate (AER) < or = 20 micrograms/min in > or = 2 overnight urine collections), 10 developed microalbuminuria with an incidence density of 6.5 cases per 100 person-years (95% CL, 2.23, 10.16). Spontaneous normalization of AER was found in 2 of 4 patients with microalbuminuria at cycle 2. Multiple stepwise regression analysis demonstrated that baseline AER (p = 0.03), but not glycated hemoglobin, blood pressure or duration of diabetes, predicted end-of-study AER. From 36 patients without retinopathy, 10 developed nonproliferative retinopathy with an incidence density of 6.6 cases per 100 person-years (95% CL, 2.75, 10.54). Retinopathy was associated with duration (p = 0.05) and age at diagnosis of diabetes (p = 0.01). A tendency with baseline AER (p = 0.06) was also noted. No patient developed macroalbuminuria, proliferative retinopathy or hypertension. By the end of our study, in a cohort of young IDDM patients followed in a developing country, 6% died from acute complications and 15 patients (44.1%) developed retinopathy and/or microalbuminuria. Our results suggest that the only predictor of end-of-study AER was baseline AER. Also, duration of diabetes and age at diagnosis appear to be risk factors for retinopathy.