Variations of blood glucose in the physiological range alter appetite, gastrointestinal sensation, and pyloric motility

Abstract

Background: Marked hyperglycemia (blood glucose [BG] ~ 15 mmol/L) slows gastric emptying, and increases both perception of gastric distension and postprandial satiation, in normal and diabetic subjects. The aim of this study was to determine whether variations in blood glucose within the physiological range (4-8 mmol/L) influence appetite, gastrointestinal sensation, and/or antropyloroduodenal motility in normal subjects. Methods: Paired studies were done in random order in 8 healthy volunteers following an overnight fast. A multilumen manometric assembly was positioned with a sleeve sensor spanning the pylorus, and either glucose or saline was infused intravenously to maintain a BG of 8 or 4 mmol/L. Antropyloroduodenal pressures were recorded in the fasting state for up to 90 minutes. An intraduodenal infusion of lipid (Intralipid 10% at 1.5 kcal/min) was then administered for 90 minutes to simulate the fed state. Appetite (hunger and desire to eat) and gastrointestinal sensation (nausea and fullness) were evaluated using visual analogue questionnaires at 15 minute intervals. Results: In the fasting state fullness was greater (P<0.05) at a BG of 8 mmol/L when compared to 4 mmol/L, but there was no difference in nausea or hunger. During intraduodenal lipid infusion, there was an increase in nausea (P<0.005) and a decrease in hunger (P<0.05) at a BG of 8 mmol/L, but not at a BG of 4 mmol/L. Intraduodenal lipid stimulated (P<0.001) isolated pyloric pressure waves (IPPWs) in both studies. The frequency (P<0.05) and amplitude (P<0.05) of IPPWs was less at a BG of 8 mmol/L than at a BG of 4 mmol/L. Conclusions: Physiological changes in blood glucose affect gastrointestinal sensation and pyloric motility. At a BG of 8 mmol/L when compared to 4 mmol/L (i) hunger is less, (ii) fullness and nausea are increased, and (iii) the stimulation of phasic pyloric pressure waves by intraduodenal lipid is attenuated.