title: Unprecedented high insulin secretion in a healthy human subject after intravenous glucagon-like peptide-1: a case report.
abstract: BACKGROUND
  The gut-derived incretin hormones, glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1, are released in response to ingestion of nutrients. Both hormones are highly insulinotropic in strictly glucose-dependent fashions and glucagon-like peptide-1 is often referred to as one of the most insulinotropic substances known.
  
  
  METHODS
  Plasma insulin and C-peptide concentrations were measured in a healthy Caucasian male (age: 53 years; body mass index: 28.6 kg/m2; fasting plasma glucose: 5.7 mM; 2 h plasma glucose value following 75 g-oral glucose tolerance test: 3.5 mM; glycated haemoglobin A1c: 5.5%) during glucagon (1 mg) and meal (2,370 kJ) tests, and during two 2 h 15 mM-hyperglycaemic clamps with continuous intravenous infusion of glucagon-like peptide-1 (1 pmol/kg/min) and glucose-dependent insulinotropic polypeptide (4 pmol/kg/min), respectively. Normal insulin and C-peptide responses were observed during meal test (peak concentrations: 300 and 3,278 pM) and glucagon test (peak concentrations: 250 and 2,483 pM). During the hyperglycaemic clamp with continuous intravenous infusion of GLP-1 the subject exhibited plasma insulin and C-peptide concentrations of 13,770 and 22,380 pM, respectively.
  
  
  CONCLUSIONS
  To our knowledge insulin and C-peptide concentrations of these magnitudes have never been reported. Thus, the present data support the view that glucagon-like peptide-1 is one of the most insulinotropic substances known.
authors.affiliation: Diabetes Research Division, Department of Medicine, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark. filipknop@dadlnet.dk.
authors.forename: Filip K
authors.initials: FK
authors.lastname: Knop
authors.forename: Asger
authors.initials: A
authors.lastname: Lund
authors.forename: Sten
authors.initials: S
authors.lastname: Madsbad
authors.forename: Jens J
authors.initials: JJ
authors.lastname: Holst
authors.forename: Thure
authors.initials: T
authors.lastname: Krarup
authors.forename: Tina
authors.initials: T
authors.lastname: Vilsbøll
mesh_terms: D001786:Blood Glucose / Q000032:analysis; D052216:Glucagon-Like Peptide 1 / Q000008:administration & dosage*; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion
chemical_list: D001786:Blood Glucose; D052216:Glucagon-Like Peptide 1; D006442:Glycated Hemoglobin; D007328:Insulin; C517652:hemoglobin A1c protein, human