Effects of intraduodenal glucose and fructose on antropyloric motility andappetite in healthy humans

Oral fructose empties from the stomach more rapidly and may suppress food i ntake more than oral glucose. The purpose of the study was to evaluate the effects of intraduodenal infusions of fructose and glucose on antropyloric motility and appetite. Ten healthy volunteers were given intraduodenal infu sions of 25% fructose, 25% glucose, or 0.9% saline (2 ml/min for 90 min). A ntropyloric pressures, blood glucose, and plasma insulin, gastric inhibitor y peptide (GIP), and glucagon-like peptide-1 (GLP-1) were measured concurre ntly; a buffet meal was offered at the end of the infusion. Intraduodenal f ructose and glucose suppressed antral waves (P < 0.0005 for both), stimulat ed isolated pyloric pressure waves (P < 0.05 for both), and increased basal pyloric pressure (P = 0.10 and P < 0.05, respectively) compared with salin e, without any significant difference between them. Intraduodenal glucose i ncreased blood glucose (P < 0.0005), as well as plasma insulin (P < 0.0005) and GIP (P < 0.005) more than intraduodenal fructose, whereas there was no difference in the GLP-1 response. Intraduodenal fructose suppressed food i ntake compared with saline (P < 0.05) and glucose (P = 0.07). We conclude t hat, when infused intraduodenally at 2 kcal/min for 90 min 1) fructose and glucose have comparable effects on antropyloric pressures, 2) fructose tend s to suppress food intake more than glucose, despite similar GLP-1 and less GIP release, and 3) GIP, rather than GLP-1, probably accounts for the grea ter insulin response to glucose than fructose.