A First Exploratory Study of Glycemic Outcomes During Normobaric Hypoxia Simulating Moderate-Altitude Conditions in...

Physical activity is essential in type 1 diabetes mellitus (T1DM) management, and hybrid closed-loop (HCL) insulin systems are now a preferred therapy. Data on the short-term metabolic effects of hypoxia remain limited.

This study evaluated the MiniMed 780G (MM780G) system in 12 men with T1DM (mean age 40.2 ± 3.9 years; diabetes duration 22.3 ± 8.7 years; glycated hemoglobin 6.4 ± 0.6%) before, during, and after 48 hours of simulated normobaric hypoxia, with a secondary aim of comparing selected biochemical markers with 13 age- and body mass index-matched healthy men. All participants underwent a 48-hour exposure to normobaric hypoxia in a normobaric chamber, simulating an altitude of up to 3500 m a.s.l. while maintaining normal barometric pressure. A broad panel of endocrine, immunological, vascular, neurotrophic, gastrointestinal, and oxidative biomarkers was assessed to characterize whole-body adaptation to hypoxia.

Across the three study periods, a numerical difference was observed only for SD, which was higher after the test compared with the hypoxia period itself in this exploratory analysis. No significant differences were found in other glycemic indices, daily carbohydrate intake, total insulin delivery, or the proportion of insulin administered as boluses (borderline significance); however, all changes remained within recommended glycemic thresholds. Insulin-like growth factor 1 (IGF-1) levels, at both baseline and delta, tended to be higher in the T1DM group, while changes in E-selectin were more pronounced than in controls.

In this exploratory study, 48-hour exposure to normobaric hypoxia simulating an altitude of 3500 m a.s.l. was not associated with statistically significant deterioration in glycemic control in men with well-controlled T1D treated with the MM780G system, with the exception of SD, suggesting that the recovery phase rather than the exposure period may represent the higher-risk window. However, this change did not translate into deviations from recommended glycemic ranges and warrants further investigation. Biomarker profiles revealed no significant differences in inflammation, stress response, or oxidative damage compared with healthy participants. Alterations in IGF-1 and E-selectin may indicate effective compensatory and adaptive mechanisms to moderate hypoxia in people with T1DM.