Predictors for the development of microalbuminuria and macroalbuminuria in patients with type 1 diabetes: Inception cohort study

Objective: To evaluate baseline predictors for the development of persistent microalbuminuria and macroalbuminuria prospectiveli in patients with type 1 diabetes. Design: Prospective observational study of an inception cohort. Setting: Outpatient diabetic clinic in a tertiary referral centre, Gentofte, Denmark. Participants: 286 patients (216 adults) newly diagnosed with type 1 diabetes consecutively admitted to the clinic between 1 September 1979 and 31 August 1984. Main outcome measures: Persistent microalbuminuria and persistent macroalbuminuria. Results: During the median follow up of 18.0 years (range 1.0-21.5 years), total of 4706 patient years of follow up, 79 of 277 patients developed persistent microalbuminuria. 27 progressed further to persistent macroalbuminuria. The cumulative incidence of persistent microalbuminuria and persistent macroalbuminuria was 33.6% (95% confidence interval 27.2% to 40.0%) and 14.6% (8.9% to 20.3%), respectively. Significant predictors (95% confidence intervals) for the development of persistent microalbuminuria were a 10-fold increase in urinary albumin excretion rate (relative risk 3.78, 1.57 to 9.13), being male (2.41, 1.43 to 4.06), a 10 mm Hg increase in mean arterial blood pressure (138, 1.20 to 1.57), a 1% increase in haemoglobin A_1c (1.18, 1.04 to 1.32), and a 1 cm increase in height (0.96, 0.95 to 0.98). 28 patients with microalbuminuria (35%) regressed to normoalbuminuria either transiently (n = 15) or permanently (n = 13). Conclusions: Around one third of patients newly diagnosed with type 1 diabetes develop persistent microalbuminuria within the first 20 years of diabetes. Several potentially modifiable risk factors predict the development of persistent microalbuminuria and persistent macroalbuminuria.