CGM and diving

[reefugee]

I am diabetic type 2 and use a constant glucose monitor (CGM). Before I went to Cozumel, I searched to see if a CGM works after scuba diving. I didn't find any information.

I am glad to report that my FreeStyle Libre 2 sensor continued to work after 5 days of diving (2 dives per day). The deepest depth was about 90ft. I was wearing a shortie.


Keywords: diabetes, CGM, FreeStyle Libre 2, Dexcom G6 (Note, I did not test the Dexcom.)

 

[mdanser]

(Nondiabetic) I also have worn a CGM while diving with no issue. The sensor is encapsulated and seems water tight enough at depth.

 

[Duke Dive Medicine]

I am diabetic type 2 and use a constant glucose monitor (CGM). Before I went to Cozumel, I searched to see if a CGM works after scuba diving. I didn't find any information.

I am glad to report that my FreeStyle Libre 2 sensor continued to work after 5 days of diving (2 dives per day). The deepest depth was about 90ft. I was wearing a shortie.


Keywords: diabetes, CGM, FreeStyle Libre 2, Dexcom G6 (Note, I did not test the Dexcom.)

It's always best to check the manufacturer's guidelines, which often contain information about a device's pressure tolerance. You said that your sensor continued to work, by which I'm guessing you mean that it continued to give you glucose readings. Did you verify its accuracy against a glucometer?

Best regards,
DDM

 

[VThokieChE]

I am diabetic type 2 and use a constant glucose monitor (CGM). Before I went to Cozumel, I searched to see if a CGM works after scuba diving. I didn't find any information.

I am glad to report that my FreeStyle Libre 2 sensor continued to work after 5 days of diving (2 dives per day). The deepest depth was about 90ft. I was wearing a shortie.


Keywords: diabetes, CGM, FreeStyle Libre 2, Dexcom G6 (Note, I did not test the Dexcom.)

I just returned from 2 weeks in Fiji, deepest dive of 105ft, 23 dives,, and maintained accurate readings with my Dexcom G6.

 

[Duke Dive Medicine]

I just returned from 2 weeks in Fiji, deepest dive of 105ft, 23 dives,, and maintained accurate readings with my Dexcom G6.

@Katie Davis , thanks for sharing this, may I ask whether you compared your CGM readings to a standard glucometer to make sure they were accurate? Did you get any information from the manufacturer about diving with the device?

Best regards,
DDM

 

[VThokieChE]

@Katie Davis , thanks for sharing this, may I ask whether you compared your CGM readings to a standard glucometer to make sure they were accurate? Did you get any information from the manufacturer about diving with the device?

Best regards,
DDM

I did check with my finger-stick glucometer and it was within the 20 units allowable error. The biggest discrepancy was 74 on the dexcom compared to 91 on the glucometer between dives, but I'd had juice after surfacing, and since the dexcom readings are about 15 minutes behind the glucometer, I found that pretty typical of normal use.
Honestly, the dexcom had more trouble with accuracy on the flights than diving.
Officially Dexcom says it's waterproof up to 8' for 24 hours. Since I am at the end of life for the transmitter, I figured it was worth experimenting since internet research had shown other users had some success, but none reported as deep as 105'.

I also used expression med patches to help with adhesion, and it was under my wetsuit on my upper arm. I had previously done a dive without my wetsuit, and while the transmitter didn't have any problems connecting when I surfaced, the adhesive didn't hold up, and it popped off when I got out of the water.

 

[Duke Dive Medicine]

I did check with my finger-stick glucometer and it was within the 20 units allowable error. The biggest discrepancy was 74 on the dexcom compared to 91 on the glucometer between dives, but I'd had juice after surfacing, and since the dexcom readings are about 15 minutes behind the glucometer, I found that pretty typical of normal use.
Honestly, the dexcom had more trouble with accuracy on the flights than diving.
Officially Dexcom says it's waterproof up to 8' for 24 hours. Since I am at the end of life for the transmitter, I figured it was worth experimenting since internet research had shown other users had some success, but none reported as deep as 105'.

I also used expression med patches to help with adhesion, and it was under my wetsuit on my upper arm. I had previously done a dive without my wetsuit, and while the transmitter didn't have any problems connecting when I surfaced, the adhesive didn't hold up, and it popped off when I got out of the water.

@Katie Davis thank you for those details. I would always go with the manufacturer guidelines for your CGM equipment. If you're outside those, there is no way to tell if, when, and by how much it will fail, though it sounds like this was more of an experiment on your part with your finger stick glucometer as backup.

I'm also linking the DAN guidelines for diving with diabetes for general readership and in case you weren't already aware of them. There is some guidance on when to delay diving based on glucose readings.

Best regards,
DDM

 

[bvanant]

The chemistry of the CGM should not be affected by pressure in any way and if the device remains water tight it should work fine. However the Dexcom and Medtronic CGM use an enzyme that has some oxygen dependency so diving on high concentrations of Nitrox Might raise the reading a tiny bit. We routinely test sensors at low oxygen concentrations to mimic the in-vivo environment but don't typically test them at higher than atmospheric oxygen levels. It would be interesting to measure local tissue oxygen under nitrox conditions.
Bill

 

[extremetito]

I was also concerned about the effects of depth on my CGM (Dexcom G6), but my experience has been similar to those stated here. I did 2 dives in Guam in June/2022, and 4 dives in the Philippines October/2022. The deepest dive was around 80 ft. I did cover the CGM with Tegaderm for added protection. No significant amount of water accumulated under the membrane. The CGM functioned normally during and after.

 

[Old Timer]

Glad to hear of the successes with CGM. I have Freestyle Libre 3 and will be trying it out underwater in the Cayman islands in March 2025.