OBJECTIVE To describe the relations between glycemic control and development of diabetic nephropathy (DN) in patients with non-insulin-dependent diabetes mellitus (NIDDM). METHODS A retrospective analysis was carried out on two groups of NIDDM patients, one group without proteinuria (< 300 mg/day, n = 106) and the other group with proteinuria (> or = 500 mg/day, n = 106). The two groups were matched by age <or= +/- 3yrs, sex, race and resident place. Information of these subjects including demographic, history of diseases, family history of diseases, life-style and behavior style was obtained by self-administered questionnaire. Variables including systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting blood glucose (FBG), quantity of protein in 24-h urine were measured. Successful glycemic control denoted that the mean value of FBG's surveillance was less than 140 mg/dl after the occurrence of DM (the duration to the development of DN for the patients with DN.). Conditional logistic regression analysis was carried out. RESULTS Results from univariate analysis showed that development of proteinuria was associated with glycemic control, the FBG level at diagnosis of NIDDM and the highest FBG level in the past. The corresponding odd ratios (OR) with 95% confidence intervals (CI) were 0.43 (0.25 - 0.75); 1.34 (1.05 - 1.72) and 1.35 (1.07 - 1.70) respectively. When data were adjusted by possible confounding factors, the relation of glycemic control to DN still existed, but the other two relations disappeared. CONCLUSION Successful glycemic control decreased the occurrence risk of DN, independent of other risk factors including diabetic duration.