Intravenous amino acids (IVAAs) are able to stimulate gastric acid secretion. We investigated the effect of concomitant intravenous infusion of glucose, leading to hyperglycemia, on gastric acid secretion induced by IVAAs. Seven healthy volunteers were studied twice, once during normoglycemia and once during acute hyperglycemia with blood glucose concentrations stabilized at approximately 15 mmol/L. Amino acids were infused intravenously at the rate of 10 g/h for 180 min. Acid output was measured by continuous aspiration using a recovery markers. Serum gastrin and plasma pancreatic polypeptide (PP) concentrations were determined at regular intervals. IVAAs significantly stimulated acid output compared with basal values (2.3 +/- 0.2 and 1.4 +/- 0.4 mmol/15 min, respectively, P < 0.05), release of gastrin, and PP during normoglycemia. Hyperglycemia completely inhibited (P < 0.05) IVAA-induced gastric acid output and significantly inhibited (P < 0.05) release of gastrin and PP. We conclude that IVAAs stimulate gastric acid secretion, and gastrin and PP release; acute hyperglycemia reduces IVAA-stimulated acid output, and gastrin and PP release; and circulating nutrients influence gastric acid and gastrointestinal hormone secretion.