Determinants of progression of microalbuminuria in adolescents with IDDM

OBJECTIVE - To evaluate the significance of microalbuminuria in adolescents with IDDM and to study the relative importance of blood pressure (BP), metabolic control, and albumin excretion rate (AER) on progression of microalbuminuria. RESEARCH DESIGN AND METHODS - A cohort of 155/156 children and adolescents followed from onset up to 18.3 years of IDDM participated. In a previous Follow-up in July 1991 (up to 15 years of duration), 17 patients had developed persistent microalbuminuria (greater than or equal to 20 mu g/min). In these adolescents, we analyzed whether microalbuminuria had progressed (in mean greater than or equal to 5% per year), had remained unchanged, or had normalized (<20 mu g/min) after another 3 years. The predictive values of mean HbA(1c) diastolic blood pressure (dBP), systolic blood pressure (sBP), overnight AER, sex, age, and duration of diabetes for the progression of microalbuminuria were determined using multiple regression modeling. RESULTS - Seven of 17 patients with microalbuminuria in July 1991 had normalized, 6 of 17 patients had progressed, and 4 of 17 patients had remained unchanged after 3 years. Progressors had higher mean HbA(1c) during the first 5 years of IDDM and higher mean sBP in 1991 than nonprogressors. Patients with normalized microalbuminuria all had AER <30 mu g/min in 1991, were younger at onset of microalbuminuria, had lower mean HbA(1c), and had lower dBP before normalized AER than nonregressors at the same duration of microalbuminuria. In multivariate analysis, independent significant predictors for progression were first 5-year mean HbA(1c), mean AER, and mean sBP in 1991 (R(2) = 0.76, P = 0.001). CONCLUSIONS - Progression of microalbuminuria in adolescents with IDDM is predicted by early sustained hyperglycemia, later elevated sBP, and increased AER per se. Microalbuminuria is frequently normalized in adolescents, and this is associated with better prevailing metabolic control, younger age, and lower dBP.