title: Hyperinsulinaemia during exercise does not suppress hepatic glycogen concentrations in patients with type 1 diabetes: a magnetic resonance spectroscopy study.
abstract: OBJECTIVE
  We compared in vivo changes in liver glycogen concentration during exercise between patients with type 1 diabetes and healthy volunteers.
  
  
  METHODS
  We studied seven men with type 1 diabetes (mean +/- SEM diabetes duration 10 +/- 2 years, age 33 +/- 3 years, BMI 24 +/- 1 kg/m(2), HbA(1c) 8.1 +/- 0.2% and VO(2) peak 43 +/- 2 ml [kg lean body mass](-1) min(-1)) and five non-diabetic controls (mean +/- SEM age 30 +/- 3 years, BMI 22 +/- 1 kg/m(2), HbA(1c) 5.4 +/- 0.1% and VO(2) peak 52 +/- 4 ml [kg lean body mass](-1) min(-1), before and after a standardised breakfast and after three bouts (EX1, EX2, EX3) of 40 min of cycling at 60% VO(2) peak. (13)C Magnetic resonance spectroscopy of liver glycogen was acquired in a 3.0 T magnet using a surface coil. Whole-body substrate oxidation was determined using indirect calorimetry.
  
  
  RESULTS
  Blood glucose and serum insulin concentrations were significantly higher (p < 0.05) in the fasting state, during the postprandial period and during EX1 and EX2 in subjects with type 1 diabetes compared with controls. Serum insulin concentration was still different between groups during EX3 (p < 0.05), but blood glucose concentration was similar. There was no difference between groups in liver glycogen concentration before or after the three bouts of exercise, despite the relative hyperinsulinaemia in type 1 diabetes. There were also no differences in substrate oxidation rates between groups.
  
  
  CONCLUSIONS
  In patients with type 1 diabetes, hyperinsulinaemic and hyperglycaemic conditions during moderate exercise did not suppress hepatic glycogen concentrations. These findings do not support the hypothesis that exercise-induced hypoglycaemia in patients with type 1 diabetes is due to suppression of hepatic glycogen mobilisation.
authors.affiliation: Centre for Integrated Systems Biology and Medicine, School of Biomedical Sciences, University of Nottingham, Nottingham, UK.|Queen's Medical Centre, Nottingham, UK.
authors.forename: K
authors.initials: K
authors.lastname: Chokkalingam
authors.affiliation: Centre for Integrated Systems Biology and Medicine, School of Biomedical Sciences, University of Nottingham, Nottingham, UK.
authors.forename: K
authors.initials: K
authors.lastname: Tsintzas
authors.affiliation: Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, UK.
authors.forename: J E M
authors.initials: JEM
authors.lastname: Snaar
authors.affiliation: Centre for Integrated Systems Biology and Medicine, School of Biomedical Sciences, University of Nottingham, Nottingham, UK.
authors.forename: L
authors.initials: L
authors.lastname: Norton
authors.affiliation: Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, UK.
authors.forename: B
authors.initials: B
authors.lastname: Solanky
authors.affiliation: Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, UK.
authors.forename: E
authors.initials: E
authors.lastname: Leverton
authors.affiliation: Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, UK.
authors.forename: P
authors.initials: P
authors.lastname: Morris
authors.affiliation: Queen's Medical Centre, Nottingham, UK.
authors.forename: P
authors.initials: P
authors.lastname: Mansell
authors.affiliation: Centre for Integrated Systems Biology and Medicine, School of Biomedical Sciences, University of Nottingham, Nottingham, UK. Ian.macdonald@nottingham.ac.uk.|School of Biomedical Sciences, Queen's Medical Centre, University of Nottingham, Derby Road, Nottingham, NG7 2UH, UK. Ian.macdonald@nottingham.ac.uk.
authors.forename: I A
authors.initials: IA
authors.lastname: Macdonald
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D006946:Hyperinsulinism / Q000209:etiology*; D007262:Infusions, Intravenous; D007328:Insulin / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology; D008112:Liver Glycogen / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D012016:Reference Values
chemical_list: D001786:Blood Glucose; D007328:Insulin; D008112:Liver Glycogen