OBJECTIVE To examine the prevalence of microalbuminuria and the relationships of microalbuminuria to blood pressure and other risk factors. RESEARCH DESIGN AND METHODS Individuals diagnosed with diabetes at ≥30 yr of age either taking insulin (n = 435) or not taking insulin (n = 363), who were participants in the population-based Wisconsin Epidemiologic Study of Diabetic Retinopathy, were examined during 1984-1986. Random urine samples were collected and an agglutination inhibition test was used to determine the presence of microalbuminuria, which is defined as ≥0.03 g/L but <0.3 g/L. RESULTS The frequency of microalbuminuria was 29.2% in those individuals taking insulin and 22.0% in those not taking insulin. Microalbuminuria was significantly associated with the male sex, older age, higher systolic blood pressure, higher GHb, use of insulin, higher recent alcohol consumption, and a history of cardiovascular disease. CONCLUSIONS These findings suggest a relationship between controllable risk factors, blood pressure and GHb, and microalbuminuria in older-onset diabetic individuals.