To further explore the effects of icodextrin solution on residual renal function, the investigators will conduct a multicenter prospective randomized controlled open-label trial. Briefly, incident or prevalent adult CAPD patients with residual urine volume > 750 ml will be included. Patients on APD will be excluded. After a 4-week screening period, patients will be randomly assigned to icodextrin or 2.5% glucose solution for the long dwell. Residual GFR and fluid status will be assessed at baseline, 6, and 12 months. Residual GFR will be calculated as an average of urea and creatinine clearance from a 24-hour urine collection. To assess fluid status, the investigators will use three different assessment tools; 1) echocardiography for measuring intra vena cava (IVC) diameter and left ventricular end diastolic diameter, 2) measurement of plasma atrial natriuretic peptide, 3) bioimpedence analysis. Primary outcome is residual GFR change at 1-year and secondary outcome is change of fluid status during the study period. Also, biochemical laboratory data such as hemoglobin, hsCRP, plasma osmolality, and lipid profile, peritoneal equilibration test, dialysis adequacy, and daily peritoneal glucose exposure will be monitored. At least 50 subjects (a total of 100) would be required for each group to detect 50% difference of residual GFR between the two groups if type I error rate is 5% and type II error is 20% given 30% of drop-out rate during the study period.