title: Whole-body heat loss during exercise in the heat is not impaired in type 1 diabetes.
abstract: OBJECTIVE
  The objective of this study is to determine whether individuals with type 1 diabetes exhibit impairments in local and whole-body heat loss responses that could affect core temperature regulation during exercise in the heat compared with matched, nondiabetic individuals.
  
  
  METHODS
  Twelve otherwise healthy individuals with type 1 diabetes (HbA1c = 7.7% ± 0.3%) and 12 controls matched for age, sex, body surface area, and physical fitness cycled continuously for 60 min at a set rate of metabolic heat production (approximately 400 W) in a whole-body direct calorimeter (35°C and 20% relative humidity). Local sweat rate (ventilated capsule) was measured on the back and skin blood flow (laser Doppler velocimetry) on the forearm. Core (rectal and esophageal) and mean skin temperatures and heart rate were measured continuously. Whole-body heat exchange and change in body heat content were measured using simultaneous direct whole-body and indirect calorimetry.
  
  
  RESULTS
  The change (mean ± SE) in body heat content was similar between groups during exercise (diabetes, 409 ± 27 kJ; control, 386 ± 33 kJ; P = 0.584) and recovery (diabetes, -115 ± 16 kJ; control, -93 ± 24 kJ; P = 0.457). Local heat loss responses of sweating (P = 0.783) and skin blood flow (P = 0.078) as well as rectal temperature (diabetes, 37.87°C ± 0.10°C; control, 37.85°C; ± 0.13°C; P = 0.977) and heart rate (diabetes, 130 ± 9 beats·min, vs control, 126 ± 8 beats·min, P = 0.326) were comparable at the end of the exercise period.
  
  
  CONCLUSIONS
  During light-to-moderate-intensity exercise performed under conditions permitting full sweat evaporation, otherwise healthy type 1 diabetic individuals did not show impaired heat loss responses during heat exposure when compared with matched individuals without diabetes.
authors.affiliation: University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Jill M
authors.initials: JM
authors.lastname: Stapleton
authors.forename: Jane E
authors.initials: JE
authors.lastname: Yardley
authors.forename: Pierre
authors.initials: P
authors.lastname: Boulay
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Sigal
authors.forename: Glen P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology*; D002151:Calorimetry; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006358:Hot Temperature; D006801:Humans; D008297:Male; D005082:Physical Exertion / Q000502:physiology*; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply; D013546:Sweating