Progression to overt proteinuria in microalbuminuric Koreans with non-insulin-dependent diabetes mellitus

Abstract

Long-term data concerning the progression of microalbuminuria are not available in Koreans with non-insulin-dependent diabetes mellitus (NIDDM). To elucidate potential risk factors of the development of overt proteinuria in microalbuminuric Koreans with NIDDM, we studied retrospectively 46 patients with NIDDM. Between 1989 and 1990, they were found to have persistent microalbuminuria, and then were followed up regularly. Urinary albumin excretion rates (UAEs) were measured on a 24-h urine sample. Microalbuminuria was defined as UAE between 20 and 200 μg/min, and overt proteinuria as UAE>200 μg/min on two consecutive occasions. After a mean of 4.5 years (range 3–6), 23 patients progressed to overt proteinuria (progressors), and others remained microalbuminuric (nonprogressors). Duration of diabetes was significantly longer in progressors than in nonprogressors. Mean fasting plasma glucose and HbA 1c levels during the follow-up were significantly higher in progressors compared with nonprogressors (11.5±3.6 vs. 8.7±2.5 mmol/l, P=0.006, and 8.9±1.5 vs. 7.5±1.4%, P=0.005, respectively). In addition, frequencies of overt proteinuria were significantly higher in patients with their mean HbA 1c>8% during follow-up than in patients with their mean HbA 1c≤8% during follow-up (65.2 vs. 30.4%, P=0.015). Mean systolic blood pressure and mean diastolic blood pressure during follow-up tended to be higher in progressors compared with nonprogressors. Multiple logistic regression analysis revealed that mean HbA 1c levels and mean systolic blood pressure during the follow-up were the most significant predictors for the incidence of overt proteinuria at 4.5-year follow-up, when adjusted for various factors ( P=0.023, P=0.038, respectively). We conclude that poor glycemic control, along with elevated systolic blood pressure, were powerful predictors for the development of overt proteinuria in microalbuminuric Koreans with NIDDM.