CGM unreliable when skiing

[cz_dave]

My kids have spring holidays this week, so we went skiing. Today has been the first day on the slopes.

By the time we got onto the slope, I had barely any bolus insulin from breakfast but my Dexcom kept reporting falling levels. So, I kept upping them with bread, juice, etc. I was able to keep them between 4 and 5 mmol.

When I got back to the hotel, Dexcom showed 5.2 but when I checked with my glucose meter, it showed 7.2.

Kind of frustrating. I know a CGM is not very reliable when one is physically active. And I have already seen this kind of behavior when skiing a few times before. I guess I will bring my meter tomorrow with me to be able to double-check.

@pinewood - I have noticed you also use Dexcom. Any comments?

 

[tim2000s]

Humm. @cz_dave, if when you blood tested you were 7.2 rather than 5.2, I'd be inclined to suggest that you may very well have needed the extra carbs...

 

[iHs]

I'm afraid that Dexcom G4 and G5 doesn't respond wonderfully quick in showing a true bg level after treating a low bg warning with glucose juice, sugar etc. It's due to time lag so best not to overtreat the low but wait about 30mins and use the reading from a blood finger stick. I tend to calibrate about 2hrs after a low otherwise there will be hours of incorrect data.

 

[Juicyj]

Hi @cz_dave - sorry no experience of a dexcom just the Libre on the slopes for me, I found it was ok for trends but not accuracy, not sure if it was the cold or simply as my BG was under going such rapid changes whilst skiing. It was good to give me peace of mind when doing a quick stop but in reporting current BG levels I didn't trust it. I personally drop my basal as well as my bolus on the pump and test every hour or so, have a good time

 

[pinewood]

My kids have spring holidays this week, so we went skiing. Today has been the first day on the slopes.

By the time we got onto the slope, I had barely any bolus insulin from breakfast but my Dexcom kept reporting falling levels. So, I kept upping them with bread, juice, etc. I was able to keep them between 4 and 5 mmol.

When I got back to the hotel, Dexcom showed 5.2 but when I checked with my glucose meter, it showed 7.2.

Kind of frustrating. I know a CGM is not very reliable when one is physically active. And I have already seen this kind of behavior when skiing a few times before. I guess I will bring my meter tomorrow with me to be able to double-check.

@pinewood - I have noticed you also use Dexcom. Any comments?

Fine for me when I went skiing; I can't say I noticed any issues. To be honest, I would not see a 5.2 and 7.2 as a particularly big deal, especially if your Dexcom caught up eventually? Don't forget that there will always a be a small time lag.

 

[cz_dave]

Thanks for everyone's comments! Today I also took my meter and used that in addition to the Dexcom. When I got to the slopes, I was at 4.9 mmol and pretty much stayed in this region for the whole afternoon. I did not have propper lunch, just some nuts, prosciutto and a little bit of bread to keep me in the range. When I got back to the hotel, my Dexcom showed 5.2 and my meter showed 5.1.

The weather was gorgeous and we had a great day.

 

[GrantGam]

I'll second @Juicyj's post. Never used CGM either, just FGM - but notice differences between actual BG and the BG estimated by the Libre sensor. Again, as already mentioned, more than likely caused by the delayed response time of the sensor vs a finger stick test when rapid BG fluctuations are happening under exercise conditions.

Glad you had a good day on the slopes, I never got out at all