title: Increased insulin requirements during exercise at very high altitude in type 1 diabetes.
abstract: OBJECTIVE
  Safe, very high altitude trekking in subjects with type 1 diabetes requires understanding of glucose regulation at high altitude. We investigated insulin requirements, energy expenditure, and glucose levels at very high altitude in relation to acute mountain sickness (AMS) symptoms in individuals with type 1 diabetes.
  
  
  METHODS
  Eight individuals with complication-free type 1 diabetes took part in a 14-day expedition to Mount Meru (4,562 m) and Mount Kilimanjaro (5,895 m) in Tanzania. Daily insulin doses, glucose levels, energy expenditure, and AMS symptoms were determined. Also, energy expenditure and AMS symptoms were compared with a healthy control group.
  
  
  RESULTS
  We found a positive relation between AMS symptoms and insulin requirements (r = 0.78; P = 0.041) and AMS symptoms and glucose levels (r = 0.86; P = 0.014) for Mount Kilimanjaro. Compared with sea level, insulin doses tended to decrease by 14.2% (19.7) (median [interquartile range]) (P = 0.41), whereas glucose levels remained stable up to 5,000 m altitude. However, at altitudes >5,000 m, insulin dose was unchanged (36.8 ± 17 vs. 37.6 ± 19.1 international units [mean ± SD] P = 0.75), but glucose levels (7.5 ± 0.6 vs. 9.5 ± 0.8 mmol/L [mean ± SD] P = 0.067) and AMS scores (1.3 ± 1.6 vs. 4.4 ± 4 points [mean ± SD] P = 0.091) tended to increase. Energy expenditure and AMS symptoms were comparable in both groups (P = 0.84).
  
  
  CONCLUSIONS
  Our data indicate that in complication-free individuals with type 1 diabetes, insulin requirements tend to increase during altitudes above 5,000 m despite high energy expenditure. This change may be explained, at least partly, by AMS.
authors.affiliation: Department of Internal Medicine, Canisius Wilhelmina Hospital, Nijmegen, the Netherlands. p.demol@aig.umcn.nl
authors.forename: Pieter
authors.initials: P
authors.lastname: de Mol
authors.forename: Suzanna T
authors.initials: ST
authors.lastname: de Vries
authors.forename: Eelco J P
authors.initials: EJ
authors.lastname: de Koning
authors.forename: Rijk O B
authors.initials: RO
authors.lastname: Gans
authors.forename: Cees J
authors.initials: CJ
authors.lastname: Tack
authors.forename: Henk J G
authors.initials: HJ
authors.lastname: Bilo
mesh_terms: D000328:Adult; D000531:Altitude; D001786:Blood Glucose / Q000187:drug effects; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy* / Q000503:physiopathology*; D002149:Energy Intake / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007328:Insulin / Q000008:administration & dosage* / Q000627:therapeutic use*; D008297:Male
chemical_list: D001786:Blood Glucose; D007328:Insulin