Effect of post-voiding urine volume on progression of renal function decline in patients with type 2 diabetes

Diabetic bladder dysfunction (DBD) is a common complication of type 2 diabetes mellitus (T2DM). The association between DBD and progression of diabetic nephropathy has not been clarified. In this study, we investigated the relationship between post-voiding residual urine (PVR) with decline in renal function in patients with type 2 diabetes. This retrospective study included 164 patients at a single center. We collected medical histories and laboratory findings of patients undergoing uroflowmetry from January 1, 2008 to October 30, 2013. Renal function was assessed by calculating the estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease (MDRD) study equation. We evaluated whether greater PVR was a risk factor for faster decline of GFR during a 1-year follow-up. The subjects' mean age was 65±12 years, duration of diabetes 12.8±8.8 years, baseline serum creatinine level 106.1±53.0 μmol/L, and eGFR was 64.6±25.2 mL/min/1.73 m(2). Mean PVR was 69.8±96.3 mL and in 17.7% of subjects, PVR>100 mL. In linear regression analysis, PVR was independently associated with GFR decrease (standardized β coefficient=0.2, P=0.009). Multiple logistic analysis showed that subjects with PVR>100 mL had a 2.8-fold higher risk of an eGFR change during 1 year higher than the median value of all subjects (95% confidence interval, 1.1-6.8; P=0.03). Increased PVR was independently associated with a more rapid decline in renal function in patients with type 2 diabetes.