title: Initially more rapid small intestinal glucose delivery increases plasma insulin, GIP, and GLP-1 but does not improve overall glycemia in healthy subjects.
abstract: The rate of gastric emptying of glucose-containing liquids is a major determinant of postprandial glycemia. The latter is also dependent on stimulation of insulin secretion by glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). Although overall emptying of glucose approximates 1-3 kcal/min, the "early phase" of gastric emptying is usually more rapid. We have evaluated the hypothesis that increased stimulation of incretin hormones and insulin by a more rapid initial rate of small intestinal glucose delivery would reduce the overall glycemic response to a standardized enteral glucose load. Twelve healthy subjects were studied on two separate days in which they received an intraduodenal (id) glucose infusion for 120 min. On one day, the infusion rate was variable, being more rapid (6 kcal/min) between t = 0 and 10 min and slower (0.55 kcal/min) between t = 10 and 120 min, whereas on the other day the rate was constant (1 kcal/min) from t = 0-120 min, i.e., on both days 120 kcal were given. Between t = 0 and 75 min, plasma insulin, GIP, and GLP-1 were higher with the variable infusion. Despite the increase in insulin and incretin hormones, blood glucose levels were also higher. Between t = 75 and 180 min, blood glucose and plasma insulin were lower with the variable infusion. There was no difference in the area under the curve 0-180 min for blood glucose. We conclude that stimulation of incretin hormone and insulin release by a more rapid initial rate of id glucose delivery does not lead to an overall reduction in glycemia in healthy subjects.
authors.affiliation: Department Medicine, University of Adelaide, Royal Adelaide Hospital, North Terrace Adelaide, South Australia 5000, Australia.
authors.forename: Reawika
authors.initials: R
authors.lastname: Chaikomin
authors.forename: Selena
authors.initials: S
authors.lastname: Doran
authors.forename: Karen L
authors.initials: KL
authors.lastname: Jones
authors.forename: Christine
authors.initials: C
authors.lastname: Feinle-Bisset
authors.forename: Deirdre
authors.initials: D
authors.lastname: O'Donovan
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Rayner
authors.forename: Michael
authors.initials: M
authors.lastname: Horowitz
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism; D005746:Gastric Emptying; D005749:Gastric Inhibitory Polypeptide / Q000097:blood*; D005934:Glucagon / Q000097:blood*; D052216:Glucagon-Like Peptide 1; D005947:Glucose / Q000493:pharmacokinetics*; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism / Q000517:prevention & control*; D007328:Insulin / Q000097:blood*; D007421:Intestine, Small / Q000378:metabolism*; D008297:Male; D010446:Peptide Fragments / Q000097:blood*; D019518:Postprandial Period; D011498:Protein Precursors / Q000097:blood*; D012016:Reference Values
chemical_list: D001786:Blood Glucose; D007328:Insulin; D010446:Peptide Fragments; D011498:Protein Precursors; D005749:Gastric Inhibitory Polypeptide; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D005947:Glucose