A Dual Stable Isotope Study of the Effect of Altitude and Simulated Flight on Glucose Metabolism in Type 1 Diabetes: A Randomized Crossover Study.

The impact of atmospheric pressure changes on glucose metabolism encountered in aviation on people with type 1 diabetes is controversial. A dual-isotope study was performed in a hypobaric chamber to simulate pressure changes experienced on commercial flights. The fasting and postprandial glucose kinetics of individuals with type 1 diabetes were evaluated across simulated in-flight cabin pressures (550 mmHg; experimental arm) and ground level (750 mmHg; control arm). The impact of ambient pressure on glucose disposal (Rd), endogenous glucose production (EGP), meal glucose appearance (Ra), and insulin concentrations were evaluated. Six male participants, aged 20-61 years, with a median BMI of 26.6 kg/m2, were studied. Baseline glucose Rd, EGP, and meal Ra values were not affected by ambient pressure changes. Postprandial glucose Rd was higher in hypobaric conditions than ground, the percent change in postprandial glucose concentration was lower, but postprandial EGP and meal Ra were not affected. Insulin concentration between 120 and 180 min was higher in the hypobaric simulation. The observed increase in glucose Rd for individuals with type 1 diabetes who were using insulin pumps may be related to the hypoxia and pressure changes experienced during flight. Because glucose profiles were unaffected, there is no evidence that insulin pump therapy is a risk factor in flight.

Article highlights: The effects of acute atmospheric pressure changes on glucose metabolism in type 1 diabetes remain controversial and may have safety implications for pilots and travelers alike. What are the differences in glucose kinetics and hormones between ground and simulated flight environments? Glucose disposal and insulin concentration are increased in response to a meal during flight, without associated changes in endogenous glucose production or meal glucose appearance rates. Pressure-related changes in insulin pump performance and hypoxia may explain these findings. Because glucose concentrations were unaffected, there is no evidence that insulin pump therapy is a risk factor in flight.