Safety and Functional Integrity of Continuous Glucose Monitoring Components After Simulated Radiologic Procedures

Christopher Thomas, John B Welsh, Spencer Lu, J Michael Gray, Christopher Thomas, John B Welsh, Spencer Lu, J Michael Gray

Abstract

Background: We investigated wearable components of the Dexcom G6 continuous glucose monitoring (CGM) System in simulated therapeutic and diagnostic radiologic procedures.

Methods: G6 transmitters were loaded with simulated glucose data and attached to sensors. Sets of sensor/transmitter pairs were exposed to x-rays to simulate a radiotherapeutic procedure and to radiofrequency (RF) and magnetic fields to simulate diagnostic magnetic resonance imaging (MRI). The x-ray simulation provided a cumulative dose of 80 Gy. The MRI simulation used RF fields oscillating at 64 or 128 MHz and magnetic fields of 1.5 or 3 T. During the MRI simulation, displacement force, induced heating, and induced currents were measured. After the simulations, bench tests were used to assess data integrity on the transmitters and responsiveness of sensors to various concentrations of aqueous glucose.

Results: Glucose concentrations reported by sensor/transmitter pairs after undergoing x-irradiation or a simulated MRI exam were similar to those from control (unexposed) devices. During the 3 T MRI simulation, the devices experienced a displacement force of 306 g, which was insufficient to dislodge the sensor/transmitter from the substrate, RF-induced heating of <2°C, and an induced current of <16 pA. Data stored on the transmitters prior to the MRI simulation remained intact.

Conclusion: Wearable components of the G6 CGM System retain basic functionality and data integrity after exposure to simulated therapeutic and diagnostic radiologic procedures. The devices are unlikely to be affected by x-irradiation used in typical imaging studies. Simulated MRI procedures create displacement force, minimal heating, and current in sensor/transmitter pairs.

Keywords: G6; MRI; continuous glucose monitoring; imaging; radiation; x-rays.

Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: The authors are employees of Dexcom, Inc.

Figures

Figure 1.
Figure 1.
Temperature change recorded by probes exposed to a 20-minute, 3 T/128 MHz simulated MRI exam. Probe 1 was adjacent to body-worn components of the G6 CGM System; Probe 2 was nonadjacent. MRI, magnetic resonance imaging.
Figure 2.
Figure 2.
Effect of MRI exposure on background signal accumulation. Shown are data accumulated by a randomly selected single sensor/transmitter pair before, during, and after a 45-minute exposure to eight different scanning sequences in a 3 T magnetic field. MRI, magnetic resonance imaging.
Figure 3.
Figure 3.
Mean currents (in picoamperes) generated by G6 sensors in response to exposure to stepwise increasing glucose concentrations ranging from 40 to 400 mg/dL. Blue, control sensor with no MRI exposure; orange, sensor exposed to a 1.5 T magnetic field; green, sensor exposed to a 3 T magnetic field. Each curve represents one randomly selected sensor. MRI, magnetic resonance imaging.

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