A Dual Stable Isotope Study of the Effect of Altitude and Simulated Flight on Glucose Metabolism in Type 1 Diabetes: A Randomized Crossover Study
Bibliographic record
Abstract
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.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.002 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".