Sorbitol is better absorbed in the small intestine when ingested concomitantly with glucose. The aim of this study was to test in situ the effect of glucose on the absorption of sorbitol in the human small intestine, using the perfusion technique. The sorbitol absorption of three test solutions, perfused in a random order, was measured in a 30-cm segment of jejunum in six healthy volunteers (4 males and 2 females). The solutions contained the same concentration of sorbitol (55 mmol/L) and increasing concentrations of D-glucose (0, 55 and 110 mmol/L). Net absorption of water increased as the glucose concentration of the solution increased and differed significantly among the three solutions. Net absorption of glucose was significantly greater for the 110 mmol/L glucose solution than for the 55 mmol/L glucose solution [23.6 +/- 1.8 vs. 11.0 +/- 1.2 mmol/(h x 30 cm), P < 0.01]. Sorbitol absorption in the jejunal segment was 5.2 +/- 1.3, 6.2 +/- 0.5 and 5.8 +/- 0.4 mmol/(h x 30 cm) for the glucose-free solution, the 55 mmol/L glucose solution, and the 110 mmol/L glucose solution, respectively. These values did not differ significantly. These results do not support the hypothesis of a facilitating effect of glucose on sorbitol absorption in the human small intestine.