Objectives of this study were to determine the prevalence of microalbuminuria and the level of glycaemic control obtained in a young Italian population-based cohort of subjects with short duration of insulin-dependent diabetes mellitus (IDDM). Out of 298 subjects with onset of IDDM in the period 1984-88, 211 were examined (71%) in 1991-92 (duration of disease 3-9 years). Microalbuminuria was defined as albumin excretion rate (AER) 20-200 micrograms min-1 in an overnight urine collection or alb/creat > 2.5 mg mmol-1 in men and > 4.5 mg mmol-1 in women in one first morning urine sample. Twelve subjects had AER 20-200 micrograms min-1 and 4 had elevated alb/creat ratio. Prevalence of microalbuminuria was 7% (95% Cl 4.0-11.1) in subjects with duration of IDDM 3-9 years and 4% (0.3-7.7) in subjects with duration 3-5 years. Only 1 microalbuminuric subject was found out of 52 aged < or = 14 years. Duration of IDDM was significantly higher (6.9 +/- 1.9 years vs 5.7 +/- 1.6, p = 0.007) and HDL-cholesterol lower (1.22 +/- 0.21 mM vs 1.42 +/- 0.34, p = 0.025) in micro- than in normoalbuminuric subjects, even after adjustment for age, systolic and diastolic blood pressure, BMI, and HbA1c. In almost 50% of the cohort, HbA1c levels were over 9%, whereas only in 10.9% HbA1c levels were lower than 6.6% (mean +3 SD). In conclusion, this Italian population-based study showed low prevalence of microalbuminuria in young subjects with short duration of IDDM, even if the glycaemic control obtained was far from ideal.