Background: Glucose polymer is an active osmotic agent that is increasingly used as an alternative to glucose in peritoneal dialysis fluids. It was recently reported that the duration of peritoneal dialysis can be extended by using glucose polymer in patients with poor ultrafiltration. We previously demonstrated that high glucose levels damage the intercellular junctions of cultured human peritoneal mesothelial cells (HPMC), but little is known about the influence of glucose polymer. Therefore, we investigated the effects of glucose polymer on the intercellular junctions of HPMC. Methods: HPMC were isolated, cultured, and identified according to the modified method of Stylianou. M199 medium was supplemented with peritoneal dialysis solutions containing 7.5% glucose polymer or 1.5, 2.5, and 4.25% glucose. After 6 h, cell viability was assessed, intercellular junction proteins were examined by immunofluorescence techniques, and the concentration of transforming growth factor-β1 in the culture supernatant was determined. Results: Glucose significantly suppressed cell viability and significantly increased transforming growth factor-β1 production when compared with control or glucose polymer cultures. Peritoneal dialysis solutions containing 4.25% glucose caused the detachment of HPMC. Immunofluorescence of intercellular junction proteins (tight junctions: ZO-1, occludin, and claudin-1; adherens junctions: β-catenin) became weak and uneven after culture with glucose. On the other hand, glucose polymer caused little change in the immunofluorescence of these proteins when compared with control cultures. Conclusions: Glucose polymer seems to be less toxic to HPMC than glucose itself, suggesting that the glucose polymer may be better for peritoneal dialysis.