A prospective study of normoalbuminuric diabetic patients was performed between 1997 and 2002 on 4097 type 1 and 6513 type 2 diabetic patients from the Swedish National Diabetes Register (NDR); mean study period, 4.6 years. The strongest independent baseline risk factors for the development of microalbuminuria (20-200 microg/min) were elevated HbA(1c) and diabetes duration in both types 1 and 2 diabetic patients. Other risk factors were high BMI, elevated systolic and diastolic BP in type 2 patients, and antihypertensive therapy in type 1 patients. A subsequent larger cross-sectional study in 2002 showed that established microalbuminuria was independently associated with HbA(1c), diabetes duration, systolic BP, BMI, smoking and triglycerides in types 1 and 2 diabetic patients, and also with HDL-cholesterol in type 2 patients. Relatively few types 1 and 2 patients with microalbuminuria achieved treatment targets of HbA(1c) < 6.5% (21-48%), BP < 130/85 mmHg (33-13%), cholesterol < 5 mmol/l (48-46%), triglycerides < 1.7 mmol/l (83-48%) and BMI < 25 kg/m(2) (50-18%), respectively. In conclusion, high HbA(1c), BP and BMI were independent risk factors for the development of microalbuminuria in types 1 and 2 diabetic patients. These risk factors as well as triglycerides, HDL-cholesterol and smoking were independently associated with established microalbuminuria. Treatment targets were achieved by a relatively few patients with microalbuminuria.