All the known diabetic patients (917) from a defined population (90,660) were called for review by a single observer. A total of 842 (92%) attended and proteinuria, identified using Albustix (0.3 g/l or more), was found in 57 cases (6.8%), but in 9 this was in association with a urinary tract infection. Diastolic blood pressure, an ulcerated or amputated lower limb, and smoking category were found to be the only significant predictors of proteinuria after a multiple logistic regression analysis. A serum creatinine greater than 150 mumol/l was found in 29 (3.8%) of the 768 diabetics in whom it was measured. However, proteinuria was only present in 7 of the diabetics with impaired renal function. In those aged less than 65 years, the prevalence of proteinuria with impaired renal function was 0.75%.