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

Background: People with diabetes-related ulcers may benefit from hyperbaric oxygen (HBO(2)) therapy and from continuous glucose monitors (CGM). Although blood glucose (BG) meters based on glucose oxidase (GO) report erroneously low values at high pO(2), 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 HBO(2) 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 HBO(2) treatment consisting of three 30-min intervals of HBO(2) 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, HBO(2) 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-HBO(2) and post-HBO(2) 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, HBO(2) exposure results in statistically significant differences in glucose measurements obtained with GO-based devices, but not a GD-based device. Standard HBO(2) treatment results in statistically significant effects on glucose concentrations. These differences are of unlikely clinical significance.