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 relationship to duration of diabetes, onset of the disease, and long-term metabolic control, have not been evaluated in a large sample of pediatric patients. RESEARCH DESIGN AND METHODS: A total of 5,722 nocturnal urinary albumin excretion rates were determined in 447 children, adolescents, and young adults with type 1 diabetes, comprising 1,821 years of observation. Excretion rates were related to duration of diabetes, age at onset of diabetes, sex, blood pressure, and metabolic control. RESULTS: Based on repeated measurements in individual patients, the positive predictive value of one sample was 76%, the negative 99.5%. After a duration of diabetes of 11 years, 5% of patients displayed persistent microalbuminuria (10% after 13 years). The duration of diabetes until persistent microalbuminuria was identical for patients with prepubertal or pubertal onset of diabetes. In addition to duration, female sex (P < 0.03) and insufficient long-term metabolic control (P < 0.03) contributed significantly and independently 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 insufficient metabolic control are especially at risk for microalbuminuria. Even if persistent microalbuminuria usually becomes evident in patients aged > 11 years, the prepubertal duration of diabetes contributes equally to this risk. Good metabolic control therefore should be aspired to from the onset of diabetes.