Acute insulin responses to intravenous glucose and GLP-1 are independent of preceding high-frequency insulin pulse-defects induced by glucose entrainment in healthy humans.
The objective of this study was to test the hypothesis that high-frequency oscillations in insulin release is a part of the mechanistic basis of a prompt and adequate insulin response to iv-glucose and GLP-1 exposure. In ten healthy subjects, five different insulin release patterns were induced for 360 min using computer-based glucose infusion (glucose delivered in a constant, a regular pulsatile, an irregular pulse frequency, an irregular pulse amplitude or a regular but very fast-pulsatile manner) in healthy subjects. The amount of glucose infused was identical in all five protocols (24 mg/kg/h). After 360 min, insulin secretion was assessed by means of a first-phase insulin secretion test (25 g glucose) and injection of GLP-1 (9 microg). By frequent blood sampling and analysis of insulin concentration, glucose-induced entrainment was evident in all protocols except in the constant infusion and the very fast-pulse protocol. The first-phase insulin release to glucose and GLP-1-induced insulin release were, however, comparable in the protocols. We therefore conclude from this short-term experimental setting in healthy subjects that beta-cell response to either iv-glucose or GLP-1 is independent of the preceding regularity of oscillations in insulin release.
Juhl
C B
CB
Medical Department M (Endocrinology and Diabetes), University Hospital of Aarhus, Noerrebrogade 44, 8000 Aarhus C, Denmark. claus.juhl@dadlnet.dk
Sturis
J
J
Hollingdal
M
M
Schmitz
O
O
D000222:Adaptation, Physiological; D000328:Adult; D001786:Blood Glucose / Q000502:physiology*; D005260:Female; D005934:Glucagon / Q000008:administration & dosage*; D052216:Glucagon-Like Peptide 1; D005947:Glucose / Q000008:administration & dosage*; D006801:Humans; D007262:Infusions, Intravenous; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D010446:Peptide Fragments / Q000008:administration & dosage*; D010507:Periodicity; D011498:Protein Precursors / Q000008:administration & dosage*; D012016:Reference Values
D001786:Blood Glucose; D007328:Insulin; D010446:Peptide Fragments; D011498:Protein Precursors; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D005947:Glucose