Between 5 and 20% of children with type 1 diabetes may develop microalbuminuria as a sign of incipient nephropathy starting in early puberty. Permanent microalbuminuria has to be distinguished from intermittent and transient microalbuminuria with unknown prognostic relevance. A review of clinical risk factors, retinal examination and an ambulatory 24-h blood pressure profile are recommended. Non-pharmacological interventions such as the improvement of glycemic control, the cessation of smoking or the feasibility of a low protein diet should always be considered. Concerning pharmacological intervention, in particular ACE-inhibitors have been shown to be beneficial in adolescents with hypertension but may also be renoprotective in normotensive patients with microalbuminuria. However, long-term studies with ACE-inhibitors in normotensive patients have shown negligible changes in the glomerular filtration rate, which better reflects the renal status during treatment than changes in the albumin excretion rate. Nevertheless, such treatment is currently recommended also for normotensive adolescents if other interventions are not successful.