RATIONALE: Standard peritoneal glucose solutions may induce the formation of advanced glycation end products (AGEs). Preliminary data suggest that AGE formation may be less with the use of polyglucose solutions (icodextrin). Therefore, we investigated whether the use of icodextrin for the long dwell would result in a reduction in plasma and dialysate levels of the AGE products N(epsilon)-(carboxymethyl) lysine (CML) and N(epsilon)-(carboxyethyl) ysine (CEL). PATIENTS AND METHODS: 40 patients were randomized to treatment with standard glucose solutions (1.36%) and icodextrin for the long dwell during a 4-month study period; 32 patients completed the study. CML was assessed by stable isotope dilution/tandem mass spectrometry. RESULTS: CML levels in plasma increased significantly in patients treated with icodextrin (0.146 +/- 0.056 at start vs 0.188 +/- 0.069 micromol/mmol Lys at the end of the study, p < 0.0001) but did not change in the control group (0.183 +/- 0.090 vs 0.188 +/- 0.085 micromol/mmol Lys). The same held true for CML levels in dialysate (0.28 +/- 0.09 at start vs 0.33 +/- 0.11 micromol/mmol Lys at the end of the study, p < 0.025). No change was observed in patients treated with the control solutions (0.31 +/- 0.11 at start vs 0.31 +/- 0.07 micromol/mmol Lys). CONCLUSION: Contrary to the hypothesis, plasma and dialysate levels of CML increased in patients treated using icodextrin for the long dwell.