Compression Low on Dexcom G6

A big thank you to the folks here on FUD! I woke up at 2:19AM last night to an angry phone alarm saying I was headed to an urgent low! It was the first time in three months of wearing a Dexcom G6. Though a little a groggy, I felt fine, and thanks to the folks here (sorry, I don’t remember who), I knew to suspect a “compression low”. Instead of reaching for glucose tabs I keep in the night stand, I did a quick check with my meter and confirmed I was fine at BG 112 and avoided spiking myself un-necessarily!

I’m a side sleeper, changed my sensor yesterday, trying the back of my arm (very comfortable BTW), and apparently laid right on top of the sensor to the point of limiting blood/fluid supply to the sensor. I’ll have to try not to do that again for the next 10 days with this sensor, and then know that sensor placement needs to be further to the inside of arm to avoid the angry alarm. Thanks again to the folks here at FUD!


Figuring things out at 2:15 in a fog isn’t easy. Good job!!


Awesome! We see this very frequently with my son…the main “tale tale sign” that you should watch for is just what you saw there…if you were level and then just suddenly seem to be taking an inexplicable nose-dive. Anytime Liam’s (my sons) alarm goes off during the night with him crossing below 100 that’s the first thing I look for…what is the trajectory and how quickly did it change, then I look at him to see how he’s sleeping. If he’s sleeping on his CGM, I just flip him over and do a finger stick, then calibrate and go back to sleep.


Good CGM tip!


FYI you shouldn’t calibrate during a compression low. You’re essentially teaching it that a low amount of fluid is a higher BG than it is. Once you adjust whatever is causing the compression, it will go back to the right value in about 15 minutes once the fluid returns.


If he is reading low and not really low I’m going to do a double calibration and continue to rage calibrate untill it listens and is reset. :slight_smile:

We have a 1% low and less than that for severe lows and we don’t do that by letting the cgm do what it wants. I control our cgm… It doesn’t control us.

If it’s bad practice I’m ok with that. I’m unconventional as it is.

Also, welcome to FUD!

You’re making in inaccurate by doing that. The sensor measures interstitial fluid. So let’s say under normal circumstances 60 units of interstitial fluid = 120 BG. (these are just made up numbers as an example)

But then you get a compression low, so your sensor only detects 40 units of fluid… so it thinks your BG is 80.

If you calibrate at that point, you’re teaching it to think that 40 units = 120 BG. Which isn’t true.

Dexcom site itself says not to calibrate when the values are changing rapidly.

You admit you’re calibrating just because you don’t won’t Clarity data to indicate your child had a low. I don’t like it either when it makes it look like my son was low. But potentially making the sensor inaccurate just to make the numbers look that is not a good trade off.

If you would let it correct itself by just waiting… you’ll notice that the G6 app and clarity data will actually go back and adjust those previously incorrect values somewhat.

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Our sensors and data are fine and we don’t have the issues with inaccurate cgm readings unless he’s reading really low or really high… Not too often. I am not advocating others follow what I do, but what i do is proven to work for us regardless of what Dexcom recommends. I also use expired insulin and all other supplies and do all kinds of other things against “the rules.”

I’m a naughty, bad boy.

Also, I know how the CGM works. You’re at FUD. :slight_smile:


Corrected this below:

I admit I’m calibrating just because I don’t won’t any systems data (Nightscout, Clarity, SugarMate, etc, etc) to indicate my child had a FALSE low.

Yes, yes I do.

Dexcom takes too long on it’s own to do anything. I take that control back.

I appreciate the “spirited” discussion and different perspectives on how to handle the situation; I’ll discuss with my Endo on recommended future handling. My initial take, admittedly without concern how anyone but me views the data, is to let the G6 fix itself as normal blood supply returns and not record a correction. It will have done it’s job and reported the event as it saw it and correct over time. I’ll know the real story and be able to relate to others as needed. But for those with others viewing the data without benefit of the back story (and perhaps thinking we all “cheat” the plan), there’s certainly room for concern these events are taken into consideration when “adjustments” to basal/bolus are considered. I’m sure there are other considerations, particularly for monitored children, that I don’t realize and haven’t even conceived. Thanks again!


As a parent who used to be constantly badgered by the Endo about lows that weren’t really lows, I took action. My fix isn’t for everyone but it is my fix for the flawed CGM system that we have. Most of the time that our son shows really high (above 250) or really low (below 60), 8 times out of 10 the CGM just isn’t correct. Finger sticks show he’s usually in the 150s when the CGM shows above 250 and he’s usually right between 85-100 when the CGM shows him low. I used to do nothing but add a note indicating this wasn’t a real low along with the correct BG via fingerstick, and I would only calibrate when BG trajectory was level or 45 degrees up or down, but this resulted in 3 - 5% FALSE lows/severe lows being shown to the Endo because the CGM takes forever to “self correct.”. I don’t have that kind of patience. So, I make our CGM display the correct BG as quickly as possible, by whatever means necessary…I don’t allow a false BG to shows any longer than necessary. This fixes the issue of the Endo nagging for something that should have never been an issue in the first place.


Must be doing something right.


Wow, I’m impressed. Wish my numbers were that good!!


Has anyone who has experience with these compression lows found a good spot for sensor placement that eliminates these compression lows?

I’ve been placing my Dexcom G6 sensor on my upper arms… sometimes on back of arm and sometimes on front. This placement works great for activity during the day. But at night the majority of nights I will get the screaming false alarms regardless of what sleep position I use. My very poor work around is to power my iPhone (dexcom ap on iPhone) down to silence the alerts and set my Omnipod 5 pump onto manual mode. Switch everything back on after awaking in the morning. Any suggestions for a winning placement of the G6 sensors to dodge these compression lows??

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