Estimated Urinary Albumin Index: A Predictor of Microalbuminuria in Type 2 Diabetes

Abstract

This study examined factors contributing to the development of microalbuminuria in diabetic patients. A total of 236 patients with Type 2 diabetes were studied: 143 were normoalbuminuric and 86 were also normotensive. Multiple regression analysis was used to identify factors influencing the urinary albumin index (UAI), an index of proteinuria based on urinary albumin adjusted for urinary creatinine. Significant factors (retinopathy, systolic blood pressure, and glycosylated haemoglobin) were used to generate a formula for estimating the log_e UAI. Target values for systolic blood pressure and glycosylated haemoglobin to maintain the urinary albumin index at or below 22 were determined for different degrees of retinopathy. Normoalbuminuric patients were followed for 3 years to evaluate their progression to microalbuminuria. Each month, blood pressure, urinary albumin and creatinine, and glycosylated haemoglobin were measured. In normotensive, normoalbuminuric patients, initial urinary albumin index and log_e UAI were significantly higher in patients who subsequently developed microalbuminuria. Patients with initial log_e UAI > 3.09 or initial glycosylated haemoglobin > 6.0% also showed greater progression to microalbuminuria. Hyperglycaemia was an independent factor for the development of microalbuminuria in Type 2 diabetes. The urinary albumin index was most significantly affected by retinopathy, systolic blood pressure, and glycosylated haemoglobin. The estimated log_e UAI calculated from these factors is a useful predictor of progression to microalbuminuria.