Background: Actual blood glucose concentrations influence gastrointestinal function. We investigated whether in healthy subjects the inhibitory effect of acute hyperglycemia on gallbladder motility is dose-dependent.
Methods: Seven healthy volunteers were studied on four separate occasions in random order during euglycemia and during hyperglycemic clamping, at 4 mmol/l, 8 mmol/l, 12 mmol/l, and 16 mmol/l, respectively. Gallbladder volumes (ultrasonography) and plasma hormone release were studied before and after ingestion of a meal.
Results: Postprandial gallbladder contraction was significantly (P < 0.05) and dose-dependently inhibited during the hyperglycemic experiments at 8, 12, and 16 mmol/l (56%+/-8%, 49%+/-8%, and 30%+/-5%, respectively) compared with euglycemia (68%+/-6%). Postprandial cholecystokinin release was significantly (P < 0.05) reduced compared with euglycemia only at a plasma glucose level of 16 mmol/l (116+/-28 versus 159+/-13 pmol x l(-1) x 120 min). Plasma pancreatic polypeptide secretion, as an indirect measure of vagal-cholinergic tone, was significantly (P < 0.05) and dose-dependently reduced during hyperglycemia at 8, 12, and 16 mmol/l.
Conclusion: In healthy subjects acute hyperglycemia significantly and dose-dependently inhibits postprandial gallbladder motility. Future studies on gallbladder motility should take into account the influence of plasma glucose, because already at postprandial glucose levels gallbladder motility is reduced.