Gastric Emptying and Release of Incretin Hormones After Glucose Ingestion in Humans

J Clin Invest. 1996 Jan 1;97(1):92-103. doi: 10.1172/JCI118411.

Abstract

This study investigated in eight healthy male volunteers (a) the gastric emptying pattern of 50 and 100 grams of glucose; (b) its relation to the phase of interdigestive motility (phase I or II) existing when glucose was ingested; and (c) the interplay between gastric emptying or duodenal perfusion of glucose (1.1 and 2.2 kcal/min; identical total glucose loads as orally given) and release of glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide-1(7-36)amide (GLP-1), C-peptide, insulin, and plasma glucose. The phase of interdigestive motility existing at the time of glucose ingestion did not affect gastric emptying or any metabolic parameter. Gastric emptying of glucose displayed a power exponential pattern with a short initial lag period. Duodenal delivery of glucose was not constant but exponentially declined over time. Increasing the glucose load reduced the rate of gastric emptying by 27.5% (P < 0.05) but increased the fractional duodenal delivery of glucose. Both glucose loads induced a fed motor pattern which was terminated by an antral phase III when approximately 95% of the meal had emptied. Plasma GLP-1 rose from basal levels of approximately 1 pmol/liter of peaks of 3.2 +/- 0.6 pmol/liter with 50 grams of glucose and of 7.2 +/- 1.6 pmol/liter with 100 grams of glucose. These peaks occurred 20 min after glucose intake irrespective of the load. A duodenal delivery of glucose exceeding 1.4 kcal/min was required to maintain GLP-1 release in contrast to ongoing GIP release with negligibly low emptying of glucose. Oral administration of glucose yielded higher GLP-1 and insulin releases but an equal GIP release compared with the isocaloric duodenal perfusion. We conclude that (a) gastric emptying of glucose displays a power exponential pattern with duodenal delivery exponentially declining over time and (b) a threshold rate of gastric emptying of glucose must be exceeded to release GLP-1, whereas GIP release is not controlled by gastric emptying.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Glucose / metabolism
  • C-Peptide / metabolism
  • Duodenum / physiology
  • Gastric Emptying / drug effects
  • Gastric Emptying / physiology*
  • Gastric Inhibitory Polypeptide / metabolism
  • Gastric Mucosa / metabolism*
  • Gastrointestinal Hormones / metabolism*
  • Gastrointestinal Motility / drug effects
  • Glucagon
  • Glucagon-Like Peptide 1
  • Glucagon-Like Peptides
  • Glucose / administration & dosage
  • Glucose / metabolism*
  • Humans
  • Insulin / metabolism*
  • Insulin Secretion
  • Male
  • Peptide Fragments / metabolism*

Substances

  • Blood Glucose
  • C-Peptide
  • Gastrointestinal Hormones
  • Insulin
  • Peptide Fragments
  • glucagon-like peptide 1 (7-36)amide
  • Gastric Inhibitory Polypeptide
  • Glucagon-Like Peptides
  • Glucagon-Like Peptide 1
  • Glucagon
  • Glucose