• Two hundred ten adolescents aged 12 to 18 years with insulin-dependent diabetes mellitus were screened for microalbuminuria (albumin excretion rate of 15 to 300 μg/min). Sixteen (7.6%) showed persistent microalbuminuria (mean albumin excretion rate of 70.9±56.2 μg/min). There were no significant differences between those with and without microalbuminuria with respect to age, sex, disease duration, and blood pressure over the previous 9 months and hemoglobin A1c level measured over the preceding 3 years. Within the group with microalbuminuria, there was no correlation between albumin excretion rate and blood pressure. However, there was a significant positive correlation between log albumin excretion rate and mean hemoglobin A1c values measured over the preceding 3 years. Our findings suggest that when microalbuminuria has developed, poorer metabolic control is associated with a higher albumin excretion rate. An actual rise in systemic blood pressure may not always precede the development of microalbuminuria.