Physiological changes in blood glucose affect appetite and pyloric motility during intraduodenal lipid infusion

Abstract

We evaluated the effects of varying blood glucose concentration within the normal postprandial range and its interaction with small intestinal nutrients on antropyloric motility and appetite. Eight healthy males (19–40 yr) underwent paired studies, with a blood glucose level of 5 or 8 mmol/l. Manometry and visual analog scales were used to assess motility and appetite, during fasting and intraduodenal lipid infusion (1.5 kcal/min). In the fasting state, antral waves were suppressed at 8 mmol/l compared with 5 mmol/l ( P = 0.018). However, pyloric motility was no different between the two blood glucose concentrations. Hunger was no different at 5 mmol/l compared with 8 mmol/l, but fullness was greater at 8 mmol/l ( P = 0.01). During intraduodenal lipid infusion, antral waves were suppressed ( P < 0.035) and isolated pyloric pressure waves (IPPWs) were stimulated ( P < 0.02) compared with during the fasting state, with no difference between blood glucose concentrations, although the temporal patterning of IPPWs varied between blood glucose concentrations. The amplitude of IPPWs was greater at 5 mmol/l compared with 8 mmol/l ( P < 0.001), and hunger decreased at 8 mmol/l compared with 5 mmol/l ( P = 0.02). We conclude that “physiological” hyperglycemia modifies gastric motor and sensory function and that synergy exists between blood glucose concentration and small intestinal nutrients in modulating gastric motility and appetite.

Mechanoreceptors of the Proximal Stomach and Perception of Gastric Distension

“…In line with previous results (24), distension of the proximal stomach triggered sensation of fullness but did not decrease hunger, suggesting that the mechanism of satiation is not simply the opposite of fullness but requires concurrent stimulation of small intestine nutrient receptors (26). Furthermore, distension of the antrum may be a more important regulatory mechanism of hunger than distension of the proximal stomach (27,28).…”

Effects of variations in intragastric volume on blood pressure and splanchnic blood flow during intraduodenal glucose infusion in healthy older subjects

“…Given that small intestinal glucose delivery was standardized, the absence of any effect of distension on the rise in blood glucose was predictable. This was, however, important to exclude, as hyperglycemia (2,26), including variations in blood glucose that are within the normal postprandial range (1,37), affects gastric motility. While elevations in blood glucose and insulin appear unlikely to play a major role in postprandial hypotension, since intravenous glucose has little, if any, effect on blood pressure and postprandial hypotension occurs in type 1 diabetic patients, who are, by definition, insulin-deficient (27,28), this does not discount the relevance of potential hormonal factors.…”

Current Concepts in Gastric Motility in Diabetes Mellitus

“…Hyperglycaemia affects both intracellular metabolic pathways as well as membrane function in neural cells. Acute changes in glycaemia, even within the normal postprandial range, substantially affect gastric, oesophageal, intestinal, and gallbladder motility [74,99,100]. Emptying of solids and liquids is slower at a glycaemia of 8 mmol/L (144 mg/dl) than 4 mmol/L (72 mg/dl) in healthy and in type 1 diabetic subjects [74].…”

“…In type 1 diabetic patients the perception of post-prandial fullness is related to glycaemia [25,58,63,76]. Even acute elevations of glycaemia within the normal postprandial range affect the perception of gastroduodenal stimuli [99,175].…”