I just got a letter from my CPAP supply company alerting me that there’s a potential issue with ResMed CPAP masks that use magnetic clasps interfering with implanted medical devices with ferromagnetic components. The letter refers to pacemakers and insulin pumps, but does not mention CGMs. It says devices could be affected if they’re within 6 inches of the mask’s magnets.
I switched this month from having a Dexcom G6 in my abdomen to putting a G7 in my arm. I sleep with my arm under the pillow, so the CGM is sometimes within the 6 inch range. I saw a post elsewhere saying that the G7 in particular uses a magnet to alert the transmitter to begin the sensor session. If you look inside the G7 applicator there’s a small circular magnet near the outer edge of the applicator. When the sensor is implanted, it detaches from the applicator and the removal of the magnet alerts the sensor to start the session. I don’t think that you can trigger it to restart a sensor session or turn the sensor off by magnetizing it again, but it does show that the transmitter uses magnetically sensitive components.
Here’s the thing: When I switched to the G7, the pump started waking me up with an alarm saying that it had lost contact with the CGM for an extended period. I shifted the position of where I keep the pump, and that’s helped, but it still happens sometimes.
I’m not certain, but I think there’s a possibility (which I reported to the FDA using the link from ResMed’s notification letter) that the magnet from the CPAP mask might be interfering with the G7 transmitter.
I’m okay. They’re sending me a new, non-magnetic mask. But I thought I’d mention it here in case anyone might have a similar issue and might not have gotten the same letter or thought about it in conjunction with a CGM.