In order to examine solute transport across the peritoneal membrane and responsiveness of the peritoneal microcirculation to a vasodilator in diabetics on continuous ambulatory peritoneal dialysis (CAPD), we obtained peritoneal clearances of urea (Curea) and creatinine (Ccr), protein concentrations in the drained dialysate (DPC), and percentage of peritoneal glucose absorption (% PGA) before and after nitroprusside (NP) addition to the dialysate in 13 diabetics (DM) and 13 nondiabetics (non-DM) matched for age, sex, body weight, and duration of CAPD. Control (before NP) Curea, Ccr, DPC, and %PGA were not different between DM and non-DM. NP significantly enhanced Curea, Ccr, and DPC in both DM and non-DM. Curea, Ccr, DPC, and %PGA after NP were again not different between DM and non-DM. The findings suggest that peritoneal solute clearances and responsiveness of the peritoneal microcirculation to NP in diabetics are not different from nondiabetics at the beginning of CAPD despite evidence for widespread vascular diseases in diabetic ESRD patients.