Microangiopathy has been observed in the peritoneum of diabetic patients, and an increase in vascular permeability to small and large molecules has been described in the skeletal muscle of diabetic patients. Therefore, we examined the peritoneal equilibration test (PET) data from 19 diabetic and 19 nondiabetic stable peritoneal dialysis (PD) patients. These two groups of patients were matched in terms of age, gender, duration of PD and hypertension, incidence of peritonitis, levels of blood pressure, degree of uremia, levels of serum lipids, hematocrit, weekly KT/V, and body surface area. Compared to the nondiabetics, the diabetics had higher dialysate-to-serum ratios or mass transfer coefficients of urea or creatinine. These differences were not related to their differences in serum sodium or glucose. Regression analysis showed that the duration of hypertension was a negative determinant of peritoneal transport of urea and creatinine in diabetic patients. Our results suggest that the diabetic patients had a higher peritoneal diffusive transport of small solutes, which was offset by their duration of hypertension.