title: Exercise capacity in subjects with type 1 diabetes mellitus in eu- and hyperglycaemia.
abstract: BACKGROUND
  Circumstantial evidence suggests that an increase in plasma glucose availability improves exercise capacity in subjects with type 1 diabetes mellitus. The aim of this study was to assess exercise capacity in eu- and hyperglycaemic conditions in subjects with type 1 diabetes.
  
  
  METHODS
  Eight moderately exercise-trained male subjects with type 1 diabetes on continuous subcutaneous insulin infusion were studied. Using identical insulin infusion rates, the patients were randomly allocated to perform two stepwise ergometer tests in eu- and hyperglycaemic clamp conditions. The primary endpoint was the peak power output; the secondary endpoints comprised the rate of perceived exertion, lactate levels, heart rate, and respiratory exchange ratio.
  
  
  RESULTS
  Eu- and hyperglycaemic clamp conditions were observed at a plasma glucose concentration of 5.3 +/- 0.6 mmol/L and 12.4 +/- 2.1 mmol/L, respectively (mean +/- SD), and remained stable throughout the physical exercise. Insulin levels were similar in both conditions. Hyperglycaemia did not result in a significant increase in the peak power output compared to euglycaemia (mean paired difference of 4.96 W, 95% CI - 11.3 to 21.2, p = 0.49). Hyperglycaemia did not have a significant impact on the secondary endpoints compared to euglycaemia. Sensitivity analyses confirmed these results.
  
  
  CONCLUSIONS
  In subjects with type 1 diabetes, exercise capacity is not influenced by hyperglycaemia. Comparable levels of lactate and similar respiratory exchange ratio suggest that an increase in extracellular glucose availability did not translate into increased intracellular glucose oxidation.
authors.affiliation: Division of Endocrinology and Diabetes, University of Bern-Inselspital, 3010 Bern, Switzerland. christoph.stettler@insel.ch
authors.forename: Christoph
authors.initials: C
authors.lastname: Stettler
authors.forename: Stefan
authors.initials: S
authors.lastname: Jenni
authors.forename: Sabin
authors.initials: S
authors.lastname: Allemann
authors.forename: Roger
authors.initials: R
authors.lastname: Steiner
authors.forename: Hans
authors.initials: H
authors.lastname: Hoppeler
authors.forename: Roman
authors.initials: R
authors.lastname: Trepp
authors.forename: Emanuel R
authors.initials: ER
authors.lastname: Christ
authors.forename: Marcel
authors.initials: M
authors.lastname: Zwahlen
authors.forename: Peter
authors.initials: P
authors.lastname: Diem
mesh_terms: D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006339:Heart Rate; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology*; D007263:Infusions, Parenteral; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D010101:Oxygen Consumption; D010809:Physical Fitness
chemical_list: D001786:Blood Glucose; D007328:Insulin