Optimal fluid delivery from carbohydrate solutions such as oral rehydration solutions or sports drinks is essential. The aim of the study was to investigate whether a beverage containing glucose and fructose would result in greater fluid delivery than a beverage containing glucose alone. Six male subjects were recruited (average age (+/-SD): 22 +/- 2 y). Subjects entered the laboratory between 0700 h and 0900 h after an overnight fast. A 600 mL bolus of 1 of the 3 experimental beverages was then given. The experimental beverages were water (W), 75 g glucose (G), or 50 g glucose and 25 g fructose (GF); each beverage also contained 3.00 g of D2O. Following administration of the experimental beverage subjects remained in a seated position for 180 min. Blood and saliva samples were then taken every 5 min in the first hour and every 15 min thereafter. Plasma and saliva samples were analyzed for deuterium enrichment by isotope ratio mass spectrometry. Deuterium oxide enrichments were compared using a 2-way repeated measures analysis of variance. The water trial (33 +/- 3 min) showed a significantly shorter time to peak than either G (82 +/- 40 min) or GF (59 +/- 25 min), but the difference between G and GF did not reach statistical significance. There was a significantly greater AUC for GF (55 673 +/- 10 020 delta per thousand vs. Vienna Standard Mean Ocean Water (VSMOW).180 min) and W (60 497 +/- 9864 delta per thousand vs. VSMOW.180 min) compared with G (46 290 +/- 9622 delta per thousand vs. VSMOW.180 min); W and GF were not significantly different from each other. These data suggest that a 12.5% carbohydrate beverage containing glucose and fructose results in more rapid fluid delivery in the first 75 min than a beverage containing glucose alone.