Dexcom/Tandem X2 -- Basal IQ "compression lows"

Greetings fellow CGMers,

I’ve been using Tandem X2 with Basal IQ for a few months now. Overall, the “predictive low glucose suspend” is a godsend.

The Dex will, however, inaccurately report low or trending-to-low glucose readings if I roll over onto my G6 while asleep. Somewhere I had a vague memory of hearing about “compression lows” – where we aren’t really low, but Dex thinks we are – apparently because compression on the sensor obstructs the normal flow of interstitial fluid to the sensor wire.

I’m guilty of wearing my Dex on my upper arm.

Normally, my overnight basal keeps me pretty level with perhaps one short interval of suspended basal. (THANK YOU, Dexcom! I love being able to sleep better!)

Occasionally, in the morning, however, I wake up to see LOTS of intervals where the basal had been suspended – easily summing to 2 hours. Then as I start my day, I’m high (due to absence of the basal “tails”) and have to spend the day catching up with basal coverage.

I’ve been T1D for nearly 50 years and have been pumping - using my abs - for at least 20 of those years. I need to give some respite to the good sites left there, so I only use my abs now for pumping.

While the “fix” for me is to NOT sleep on the Dex site, I thought the general topic might be of interest to others. Until recently, I had no awareness of this concept - so I had no idea how to mitigate it.


I have also having a problem with this. I would welcome suggestions.

I love the TandemX2 with the basal IQ. It is a life saver.