The purpose of this study was to determine the effects of acute altitude exposure on the hormonal regulation and metabolism of ingested glucose. Eight healthy subjects (5 men and 3 women; age, 26 ± 2 yrs; BMI, 23.1 ± 1.0 kg·m2) performed two 75 g oral glucose tolerance tests (∼1 week apart, in random order) 1 hour after ascent to a simulated altitude (ALT) of 4,300m and under ambient conditions (AMB, 362m). Plasma glucose, insulin, c-peptide, epinephrine (EPI) and lactate concentrations were measured in venous samples obtained from an indwelling catheter pre, 30, 60, 90 and 120 min after glucose ingestion. Glucose concentrations were lower (P<0.05) at 30 min during the ALT trial compared to AMB (6.0 ± 0.2 vs 7.1 ± 0.3 mmol·l-1, respectively). Area under the glucose response curve was also lower (P<0.05) during ALT compared to AMB (69 ± 10 vs 108 ± 19 mmol·l-1·min, respectively). Insulin and c-peptide concentrations during both ALT and AMB were increased (P<0.05) at 30 and 60 min, but no differences were observed between trials. ALT exposure resulted in an increase (P<0.05) in EPI at 60 min compared to the AMB trial (5.4 ± 0.5 vs 2.6 ± 0.2 pmol·ml-1). Lactate levels were not increased above fasting levels during either trial. In conclusion, ingestion of glucose during acute ALT exposure resulted in an attenuated glucose response, but similar pancreatic insulin response compared to AMB. The reduced glucose response at ALT may be due to the additive effect of insulin and hypoxia on glucose uptake by skeletal muscle. In addition, greater EPI release at ALT may stimulate glycogenolysis and mask the magnitude of the attenuated glucose response.
|Original language||English (US)|
|State||Published - Mar 20 1998|
ASJC Scopus subject areas
- Molecular Biology