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If you wear a CGM, do you ever experience “compression lows” – false low blood glucose alerts that happen when there is pressure placed on the sensor, typically while you’re sleeping?
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I place the sensor on my arm and I try to set it so that when I sleep on my side, there is no pressure. However, I am not always successful in placement.
False lows are not just while sleeping. Frequently the first calibration after the 2 hr warmup is very low but actual glucose can be double. EX: 44 by CGM and 88 by glucose. The same happens the last 24-36 hours of the CGMs life.
I have been wearing a sensor for approximately 5 years, and this has never happened yet.
I don’t have false lows when sleeping on my CGM, but I often stop getting readings for a few minutes at a time. Nothing serious.
I used to have alot of problems when I was miss guidedly choosing my abdomen as a site. I only use back of arms now. But back means back not side of arm. No body fat left but somehow there is enough meat left there…
I wear the G6 sensor on my abdomen. I have never slept in position where sensor could be compressed.
I typically try to place my CGM where I don’t have to worry about compression lows.
I didn’t know that was a problem. I sleep on my sensor a lot. I rarely have night lows. If I do, I treat it. I don’t wake up too high, so I believe the lows are real.
I don’t know! How would you know? What is the event on the CGM? Needs an explanation if you are going to ask such a question. I do wear a CGM and have had incidences of the CGM reporting a Tech problem and to wait up to three hours. Have discussed the error with Dexcom and they sent extra patch tape.
If you can address/explain your question to me, kit would be helpful. Thank you
Hi John –
I’m not sure I can explain it well, but I’ll give it a try. There is no “event” on the CGM. What you might see are small-ish dips in the blood sugar “line” during sleep. So, you’ll see your trend line and, every so often a little dip. But, fairly quickly, the dip will go back up to the trend line. So, overall, the trend is straight or goes down or goes up (whatever your trend for the night)… but there are “breaks” in the trend. The time this would be problematic for the sleeper is if the person keeps a tight control and they have, let’s say, an 80 blood sugar all night. The “compression low” would report the person’s blood sugar as lower. If the alarm goes off, then it’s not really a low, it’s just the sensor has been tricked into thinking the blood sugar is low. Once the compression is gone, the report of the blood sugar numbers should go back to actual blood sugar numbers.
I hope that makes sense!
Until this question I have never heard of this. I sleep on it often but never thought this could be an issue when I get a low alert (happens very seldom in any event). When an alarm wakes me I seldom take a glucose test, just set one of my preset temporary basals (changes to 10% of normal basal for one or two hours) and possibly drink one of my small cans of pineapple juice and go back to sleep.
I wear my CGM sensors on my upper ab. I always sleep on my sides, so my sensor is safe while I sleep.
Yes, I had to change to wearing the sensor right in middle of stomach above navel. Even now if I sleep on my sides it is too close and the alarm goes off, wakes me. On my arms I slept on it often.
As a matter of fact, I had a low compression this am before getting up. I had my arm on top of the sensor in my upper abdomen. Thanks to contributors on this site I was educated about compression lows.
No. Not an issue I have noticed. But I do have connection problems sometimes. Pump is to far away from phone or facing the wrong way. When I roll over, it back fills but having everything facing the same way when you toss and turn can be challenging.
Question is about CGM, not a pump
I wear an Abbott Freestyle Libre that has no alerts. I have noticed the low numbers that when the sensor is wearing down, anywhere from day 11-14 days. So when I see this happening, I just change sensors.
Thanks for asking, I thought I was the only one. It doesn’t happen often (I use the Dexcom G6), but the alert has woken me, and I see a suspicious precipitous drop on the graph. Sometimes it drops off and leads to a sensor error. I just lie on my back and wait for it to correct itself. I try to not sleep on the sensor, but that’s not always possible,
I’m surprised by the comments. I wear my G6 on the back of my arm and I get compression lows. Usually more during the first few days of new sensor. If they continue, I change sensors. They are very obvious looking at the graph. They are a sharp drop of readings for no reason. I get alarmed but the main concern regarding compression lows are when you use CIQ because your basal rate will drop to 0% during the time if you are unaware and don’t’ switch position.
My daughter will only wear her dex on her upper butt, so we do get a fair amount of compression lows. It is usually pretty obvious on the graph as a large drop out of nowhere. Always a pain to have to wait for the numbers to straighten out once I change her position, but still thankful for this amazing technology.
I don’t think it’s compression lows I’m dealing with but my Medtronic CGM frequently reads 10-20 units lower than I actually am overnight. It’s not the “dip” that’s associated with a compression low though, it just trends that way through the night.
I’ve had occasional instances where my sensor has inexplicably started trending low for no apparent reason, but I can’t say it was a “compression low”. A recalibration usually takes care of it.
I put “other” because I was not sure. I wear my Medtronic CGM primarily on my hips because that’s where I have the most cushion. I’m a side sleeper and have definitely gotten lost sensor/signal alarms overnight when I lay on it. However, I don’t recall ever noticing the sudden drop some of the Dexcom users describe here.
Most compression lows come from a dog on my lap. I think I’ve only had one while sleeping.
Compression lows rarely occur for me as I’m thin and it’s painful to lay on the sensor in my upper arm. Occasionally, a Dexcom G6 sensor will ‘plummet’ to a SG of less than 50 when BG is in range 80-120. This occurs during the day and not when sensor is compressed. After calibration (or maybe more than 1), it returns to normal operation.
I have a Freestyle Libre and get no alerts. But I notice that my BG is often low during most of the night. My endo had no explanation for it. And I had never heard of compression lows until this question. I am a very restless sleeper and often lay on the GGM. I have been on the CGM for 6 months now and am not at all happy with it. The sensors have fallen off before the end of the 2-week period several times and 3 times have given me error messages and stopped working. I will be returning to finger pricks next week.