Accuracy of Dexcom G6® and FreeStyle Libre® Sensors in Standardized Hypoxia Conditions: A Randomized Controlled Trial-FOX Study.
Nathanaël Bassas Letissier, Christophe Rault, Corentin Faucher et al.
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In 30 seconds
This randomized controlled trial assessed FreeStyle Libre and Dexcom G6 accuracy during standardized normobaric hypoxia (inspired oxygen fraction 14.5%) in 30 healthy volunteers and participants with diabetes. Sensors were compared with venous plasma glucose during meal- and exercise-induced glucose changes. Under hypoxia, mean absolute relative difference was 21.2% for FreeStyle and 41.8% for Dexcom in healthy volunteers, and 11.8% and 17.5%, respectively, in participants with diabetes. Both systems showed reduced accuracy, particularly during dynamic glycemic changes.
Key findings
- During hypoxia, MARD was 21.2% for FreeStyle and 41.8% for Dexcom in healthy volunteers.
- Among participants with diabetes, hypoxia MARD was 11.8% for FreeStyle and 17.5% for Dexcom.
- During hypoxia, 97% of FreeStyle and 87% of Dexcom readings were in consensus error grid zones A or B.
Why it matters
Hypoxia can occur during altitude exposure, air travel, or certain medical conditions, and reduced sensor accuracy may affect interpretation of glucose readings. The findings highlight that performance under these conditions may differ from normoxic accuracy, especially when glucose is changing, and that automated insulin delivery implications remain uncertain.
What to keep in mind
The study included 30 participants and evaluated sensors under standardized normobaric hypoxia; its findings may not represent all real-world hypoxic conditions.