Eight subjects were exposed to a hypobaric (258 mm. Hg)-hyperoxic (100 per cent oxygen) environment for thirty days. Standard oral glucose tests were done during a control period of normal pressure and atmosphere, twenty-four hours after completing the thirty-day exposure and during a fifteen-day recovery. Exercise was uniform during the control period; however, during exposure and recovery periods four subjects continued daily exercise and the other four were maintained on limited activity (bedrest with bathroom privileges). Diet was constant throughout, containing 350 gm. of carbohydrates. Mean exposure period fasting (104.5 ± 6.5 mg./100 ml. S.E.M.) and sixty-minute (145 ± 18.5 mg./100. ml.) glucose values were significantly greater than corresponding control period fasting (87.1 ± 1.6 mg./ 100 ml.) and sixty-minute (105 ± 4.6 mg./100 ml.) control values. Mean plasma glucose values at 120 and 180 minutes during exposure to the test atmosphere were greater, but not significantly different than during control periods. Results of the glucose tolerance tests done fifteen days postexposure showed mean fasting 60-, 120- and 180-minute values to be significantly higher than the pre-exposure controls but similar to the exposure values. Serum immunoreactive insulin concentrations immediately after exposure and during recovery were unchanged from control levels. No difference in either glucose or insulin values could be detected between the exercise and nonexercise groups. It is suggested that prolonged exposure to hypobaric-hyperoxic environments adversely influences glucose tolerance.

This content is only available via PDF.