Urinary excretion of albumin in adolescents with type 1 diabetes - Persistent versus intermittent microalbuminuria and relationship to duration of diabetes, sex, and metabolic control

OBJECTIVE - Urinary excretion of albumin is a marker for incipient diabetic nephropathy in adults. The intra-individual variability, as well as the re lationship to duration of diabetes, onset of the disease, and long-term met abolic control, have not been evaluated in a large sample of pediatric pati ents. RESEARCH DESIGN AND METHODS - A total of 5,722 nocturnal urinary albumin ex cretion rates were determined in 447 children, adolescents, and young adult s with type 1 diabetes, comprising 1,821 years of observation. Excretion ra tes were related to duration of diabetes, age at onset of diabetes, sex, bl ood pressure, and metabolic control. RESULTS - Based on repeated measurements in individual patients, the positi ve predictive value of one sample was 76%, the negative 99.5%. After a dura tion of diabetes of 11 years, 5% of patients displayed persistent microalbu minuria (10% after 13 years). The duration of diabetes until persistent mic roalbuminuria was identical for patients with prepubertal or pubertal onset of diabetes. In addition to duration, female sex (P < 0.03) and insufficie nt long-term metabolic control (P < 0.03) contributed significantly and ind ependently to urinary albumin excretion. CONCLUSIONS - Determination of urinary albumin excretion rate is useful in pediatric patients. Female subjects with a long duration of diabetes and in sufficient metabolic control are especially at risk for microalbuminuria. E ven if persistent microalbuminuria usually becomes evident in patients aged >11 years, the prepubertal duration of diabetes contributes equally to thi s risk. Good metabolic control therefore should be aspired to from the onse t of diabetes.