title: Metabolic and hormonal response to intermittent high-intensity and continuous moderate intensity exercise in individuals with type 1 diabetes: a randomised crossover study.
abstract: OBJECTIVE
  To investigate exercise-related fuel metabolism in intermittent high-intensity (IHE) and continuous moderate intensity (CONT) exercise in individuals with type 1 diabetes mellitus.
  
  
  METHODS
  In a prospective randomised open-label cross-over trial twelve male individuals with well-controlled type 1 diabetes underwent a 90 min iso-energetic cycling session at 50% maximal oxygen consumption ([Formula: see text]), with (IHE) or without (CONT) interspersed 10 s sprints every 10 min without insulin adaptation. Euglycaemia was maintained using oral (13)C-labelled glucose. (13)C Magnetic resonance spectroscopy (MRS) served to quantify hepatocellular and intramyocellular glycogen. Measurements of glucose kinetics (stable isotopes), hormones and metabolites complemented the investigation.
  
  
  RESULTS
  Glucose and insulin levels were comparable between interventions. Exogenous glucose requirements during the last 30 min of exercise were significantly lower in IHE (p = 0.02). Hepatic glucose output did not differ significantly between interventions, but glucose disposal was significantly lower in IHE (p < 0.05). There was no significant difference in glycogen consumption. Growth hormone, catecholamine and lactate levels were significantly higher in IHE (p < 0.05).
  
  
  CONCLUSIONS
  IHE in individuals with type 1 diabetes without insulin adaptation reduced exogenous glucose requirements compared with CONT. The difference was not related to increased hepatic glucose output, nor to enhanced muscle glycogen utilisation, but to decreased glucose uptake. The lower glucose disposal in IHE implies a shift towards consumption of alternative substrates. These findings indicate a high flexibility of exercise-related fuel metabolism in type 1 diabetes, and point towards a novel and potentially beneficial role of IHE in these individuals.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT02068638 FUNDING: Swiss National Science Foundation (grant number 320030_149321/) and R&A Scherbarth Foundation (Switzerland).
authors.affiliation: Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland.
authors.forename: Lia
authors.initials: L
authors.lastname: Bally
authors.affiliation: Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Zueger
authors.affiliation: Department Clinical Research and Department of Radiology, University of Bern, Bern, Switzerland.
authors.forename: Tania
authors.initials: T
authors.lastname: Buehler
authors.affiliation: Department Clinical Research and Department of Radiology, University of Bern, Bern, Switzerland.
authors.forename: Ayse S
authors.initials: AS
authors.lastname: Dokumaci
authors.affiliation: Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Speck
authors.affiliation: Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland.
authors.forename: Nicola
authors.initials: N
authors.lastname: Pasi
authors.affiliation: Department of Radiology, University Hospital Centre and University of Lausanne, Lausanne, Switzerland.|Signal Processing Core, Centre for Biomedical Imaging (CIBM), Lausanne, Switzerland.
authors.forename: Carlos
authors.initials: C
authors.lastname: Ciller
authors.affiliation: Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland.
authors.forename: Daniela
authors.initials: D
authors.lastname: Paganini
authors.affiliation: Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland.
authors.forename: Katrin
authors.initials: K
authors.lastname: Feller
authors.affiliation: Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland.
authors.forename: Hannah
authors.initials: H
authors.lastname: Loher
authors.affiliation: Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Robin
authors.initials: R
authors.lastname: Rosset
authors.affiliation: Preventive Cardiology and Sports Medicine, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Wilhelm
authors.affiliation: Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Luc
authors.initials: L
authors.lastname: Tappy
authors.affiliation: Department Clinical Research and Department of Radiology, University of Bern, Bern, Switzerland.
authors.forename: Chris
authors.initials: C
authors.lastname: Boesch
authors.affiliation: Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland. christoph.stettler@insel.ch.
authors.forename: Christoph
authors.initials: C
authors.lastname: Stettler
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D002395:Catecholamines / Q000097:blood; D018592:Cross-Over Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000503:physiopathology*; D004734:Energy Metabolism / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D011446:Prospective Studies; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D002395:Catecholamines; D019344:Lactic Acid; D013006:Growth Hormone
keywords: Carbohydrate metabolism; Exercise; Hypoglycaemia; Metabolic physiology in vivo