Simultaneous recording of duodenal motility and biliary scintigraphy by continuous infusion of 99mTc-dimethyl-iminodiacetic acid was performed in 16 healthy fasted men, of whom eight had an intravenous glucose bolus injection immediately after the passage of a duodenal phase III of the migrating motor complex (MMC). This was followed by a continuous intravenous infusion of glucose. Characteristics of the time-activity curves from the gallbladder area and intestinal area were related to phase activity of the duodenal MMC. The median duration of the entire MMC cycle was significantly shorter in the glucose group than in the group without glucose. The difference was caused by shortening of phase II. Spontaneous gallbladder emptying appeared in all eight subjects from the group without glucose but in only a single subject from the glucose group. The relative amount of liver bile diverted to the gallbladder in the entire cycle was significantly higher in the subjects who received glucose, and in four subjects all the hepatic bile was diverted to the gallbladder. The results demonstrate that induced hyperglycaemia exerts a pronounced effect on gastrointestinal motility and bile kinetics. Available evidence suggests that the effects are caused by a 'medical vagotomy'.