Objectives: Peritoneal dialysis patients are at risk of glucose absorption from peritoneal dialysate, not only because of energy imbalance but also the toxic effects of high glucose. The current widely applied formulae may be not suitable for estimation of glucose absorption in continuous ambulatory peritoneal dialysis (CAPD) patients. This study examined the actual glucose absorption in a cohort of CAPD patients and compared the results with estimates from four current formulae. Methods: We conducted a survey of glucose absorption of a cohort of 72 CAPD patients and compared actual dialysate glucose absorbed and estimates using K/DOQI formula, Grodstein formula, Bodnar formula, or a percentage estimate of 60%. Results: The total dialysate glucose infused each day varied from 54.4 to 191 g/day with average of 102 +/- 27.9 g. The average of glucose absorbed was 65.7 g (ranging from 19.5 to 131 g) by actual measurements. The mean absorption rate was 64.4% (ranging from 30.6% to 92.4%). The glucose absorbed from dialysate accounted for 13.8% (ranging from 5.0% to 30.1%) of total energy intake. The average errors of absolute values between actual measurements and estimates were greater than 10 g or 20 g glucose (p<0.001). The average errors in percentages were greater than 20% or 40%, dependently on estimating methods. Conclusions: The applications of current estimating methods may have limitations. The actual measurement provides dietitians and doctors with more exact information of absorbed glucose and energy compared to the current estimating methods.