Small-solute clearances in diabetic subjects on continuous ambulatory peritoneal dialysis: comparison to nondiabetic...

Normalized clearances for urea and creatinine were compared between 121 diabetic subjects (256 clearances) and 181 nondiabetic subjects (357 clearances) on continuous ambulatory peritoneal dialysis (CAPD) with four 2-L exchanges daily. Urea clearance was normalized by VWatson (Kt/Vur), while creatinine clearance was normalized by both VWatson (Kt/Vcr) and body surface area (Ccr). Height, weight, body water (V), and body surface area did not differ between the diabetic and the nondiabetic groups. Also, renal Kt/Vur, renal Kt/Vcr, renal Ccr, and peritoneal Kt/Vur did not differ between the groups. Weekly peritoneal Kt/Vcr (diabetic group 1.36 +/- 0.38, nondiabetic group 1.31 +/- 0.31, p = 0.048) and weekly peritoneal Ccr (diabetic group 47.6 +/- 11.0 L/1.73 m2, nondiabetic group 45.4 +/- 9.2 L/1.73 m2, p = 0.012) were both higher in diabetic subjects. The percentage of high/high-average transporters was higher in the diabetic group (64.9% vs 48.6% in nondiabetic group, p = 0.006). The following total (peritoneal + renal) weekly clearances were obtained: Kt/Vur, diabetic group 2.07 +/- 0.63, nondiabetic group 2.02 +/- 0.56, NS; Kt/Vcr, diabetic group 2.06 +/- 0.78, nondiabetic group 1.92 +/- 0.74, p = 0.026; Ccr, diabetic group 72.7 +/- 28.5 L/1.73 m2, nondiabetic group 67.2 +/- 26.4 L/1.73 m2, p = 0.013. Normalized total creatinine clearances are higher in diabetic subjects than nondiabetic subjects on the same CAPD schedule and with the same renal clearances of urea and creatinine and the same total Kt/Vur, because peritoneal creatinine clearances are higher in the diabetic subjects. This finding is caused by higher peritoneal transport in the diabetic subjects and is not an artifact caused by the normalization process.