Objective: To describe the natural history of urinary albumin excretion measured initially during the first decade of type 1 diabetes in adolescents and to identify predictors of the onset and progression of microalbuminuria (MA) in this population.
Study design: A retrospective cohort follow-up study was done on 76 adolescents whose albumin excretion rate (AER) had been determined in the first decade of their diabetes. Subjects were monitored for a mean of 6 years after initial AER testing. Those with MA were compared with a group with similar age, sex, and diabetes duration who initially had normoalbuminuria (NA).
Results: Of the 28 with initial MA, 9 (32%) regressed (8 to within the NA range), whereas MA was persistent in 10 (36%) and progressed in 9 (32%), 5 to overt proteinuria. Of the 47 who had initial NA, MA developed in 14 (30%) and overt proteinuria in 3 (6%). With MA status at follow-up as the dependent variable, multiple regression analysis showed that initial AER (P =.0002) and hemoglobin A1c (P =.02) measured at the same time were significant independent variables.
Conclusions: These data suggest that in adolescents: (1) MA detected in the first decade of disease will persist or progress in the second decade in approximately two thirds of patients, and new MA will develop in a third of those initially normoalbuminuric; and (2) the appearance, persistence, or progression of MA is influenced in large part by metabolic control assessed by hemoglobin A1c both at initial MA screening and throughout the course of diabetes. This underlines the need for MA screening starting early in the course of type 1 diabetes in adolescents and for maintenance of good metabolic control.