Reliability of the Dexcom G6 Continuous Glucose Monitor during Hyperbaric Oxygen Exposure

Background: People with diabetes-related ulcers may benefit from hyperbaric oxygen (HBO₂) therapy and from continuous glucose monitors (CGM). Although blood glucose (BG) meters based on glucose oxidase (GO) report erroneously low values at high pO₂, BG meters based on glucose dehydrogenase (GD) do not. We therefore examined the performance of a GO-based CGM system in comparison to GO-based and GD-based BG systems in normobaric air (NBAir), hyperbaric air (HBAir), and HBO₂ environments. Materials and Methods: Twenty-six volunteers without diabetes mellitus (DM) wore Dexcom G6 CGM systems and provided periodic blood samples before, during, and after a standard HBO₂ treatment consisting of three 30-min intervals of HBO₂ separated by two 5-min intervals of HBAir. Accuracy of the CGM and GO-based BG meter were assessed by comparisons with the GD-based values. Results: The mean absolute relative difference for the CGM system was 15.96% and for the GO-based meter was 8.52%. Compared to NBAir, HBO₂ exposure resulted in significantly higher CGM values (+3.76 mg/dL, P < 0.001) and significantly lower GO-based meter values (-10.38 mg/dL, P < 0.001). Pre-HBO₂ and post-HBO₂ values obtained in NBAir were also significantly different when measured by CGM (+4.13 mg/dL, P = 0.015) or the GO-based meter (-9.04 mg/dL, P < 0.001). Conclusions: In volunteers without DM, HBO₂ exposure results in statistically significant differences in glucose measurements obtained with GO-based devices, but not a GD-based device. Standard HBO₂ treatment results in statistically significant effects on glucose concentrations. These differences are of unlikely clinical significance.