they went away after 15 or so min and then came up with a bg reading the was way off, then I callibrate and then get an error message and start it all over again…no finger sticks according to the commercials but I did 20 before finally giving up and starting a new one…which is warming up now…It sure is a non fun way to eat up a day. submitted my replacement request …will see how they respond…sure seem to get more than my share of bad sensors
An update 12/20/21 the site of the “bad sensor” that I replaced is totally black and blue…one of the worst looking bruises I have ever had …doesn’t hurt but really dark…when I took it off to replace with the new one I noticed that it had bled a lot…the backing fabric sticker was really saturated …so it seems i just hit it exactly right wit the canual going into/through a blood vessel which would explain , I think, the bad readings
This happens to me sometimes. The explanation is this. Inserting the sensor needle damages the tissue. The emergency healing process consumes energy from the damaged area around the sensor, i.e., it uses up a bunch of the glucose there. This shows up as a false low that can last anywhere from a few hours to a day. In my case, typically it is about 8 hours. The Dexcom algorithm tries to compensate for this but there is a great deal of variation in the individual response to the injury, so they make their error on the safe side. They read low, because that may lead you to eat carbs and raise your BG by 40 or 50 points, but that won’t hurt you. (140 instead of 100 isn’t dangerous.) If they let the error go the other way the CGM might say 80 when you actually are at 35, and that’s truly dangerous.
There’s really no point trying to calibrate during this initial period, because it’s a temporary lack of glucose around the sensor, and it will correct itself as soon as the emergency tissue repair calms down.
Some people avoid the issue by “pre-soaking” the sensor, which means to insert the new sensor several hours before the old sensor will end. Just leave the new one inserted without a transmitter while the old one continues to give readings. The emergency tissue repair calms down before you insert the transmitter into the sensor, so the errors are much smaller. I usually pre-soak 2 or 4 hours and ignore the false lows for a few hours. Others pre-soak for 12 hours to try to avoid the errors entirely. In any case, I wouldn’t try to calibrate until the sensor readings stabilize. In practice, I pretty much never calibrate because, in my body, the sensor reliably settles into accurate reading within a day.
Not everyone experiences these false low readings during the first half day, but it is pretty common, and that’s just the way it is with the current technology. We hope the G7 will be better, but who knows?
I hope so as well…my new sensor just finished warm up and it is spot on with the glucose meter reading…so it doesnt happen with all of them. but the injury theory makes sense because when I removed the sensor there was quite a lot of blood on the back which I have never had before
@bkh thanks for that explanation. I will send it along to my endo because we have all been mystified by this situation - which also happens to me occasionally. I’d assumed it was a calibration glitch but your explanation makes sense sort of I guess based on my complete ignorance of these processes…
Anyway let’s see what my endo has to say about this. Very interesting.
This happens to me often. I’ll wake up in the night with a 52 or some such. I’ve noticed when I roll over on it in my sleep I go low instantly. It only happens within the first few hours of a new sensor, so since I know that I don’t worry big I do get worried I just do a finger stick to reassure myself. The thing that’s bothering me is that every time I have a low the app doesn’t reflect it later. This is a screenshot hours after that 52. No wonder my dr thinks I never go low. Why would the app change that?
Welcome to FUD @SugarMona! I am guessing that your drops and recoveries are pretty fast and that the system is smoothing over them. If you want to read more about it, look for BillKast’s post in this thread where he does a good job of talking about the graph smoothing that Dexcom does.
I recently spoke with a Dex CSR (I usually just go through the app to report possessed sensors, but I’m pretty sure that I have a bad lot, as every single one of them has been crazy.)
So, this is what she told me:
There’s no such thing as a bad lot, just report them as I use them.
Only ever wear on abdomen.
Dexcom app does NOT change the numbers after the fact.
Calibrate EVERY TIME that its off by 20.
They can’t actually hurt, as the sensor doesn’t go in far enough.
So, I’m on a new one from the bad lot. Woke me up at 3 am, with LOW. Checked, 120. Calibrated. Seemed to be working this morning. Had a banana, but did not bolus, as I had a lot of cleaning to do. Next thing I know, Dex is showing 260 and screaming. Check, 50. Calibrate, have some sugar. 1/2 hr later, BG 70, its screaming LOW. After 4 hours of alarms and calibrations, its finally correct, but for how long?
So, basically, there’s great ones sometimes, and then ones I wear for a day, and report. Oh, yeah, and some CSRs are clearly just reading from a script.
What is quite amazing is that I think we at FUD have evidence of every one of those assertions being wrong. It is not often that a company goes to the effort to make a script where everything they say is incorrect. I may be crazy, but I think I have seen Dexcom advertising with people wearing them on the arm.
right…how long? Your experience seems just like mine. the other thing they have told me is that I just need to wait it out and eventually it will settle down…so how long is it unsafe to have totally inaccurate numbers…they didnt have an answer for that …nor could they answer how many finger sticks/callibrations they think is acceptable on one day, when I told them I was at 20+ in 12 hours they seemed to feel that was ok
How long have you been using the g6? I originally wasn’t told to report bad ones, so I spent a lot of time driving myself insane. Now I opt for the email contact, unless I feel like its something they need to know about.
A few tricks that have really helped me, all of which I learned here:
Pre-soaking really helps me. When I feel like the old one is approaching its inevitable slow and painful demise, (usually around day 7) I slap another one on.
Find the placement that works for YOU. Abdomen has never worked for me, mainly due to scars, and that’s where I bolus.
Hydrate! For me, that’s at least 2L/day.
Don’t let the Dex be your sole meter, ever. You’ll learn when to trust it. Some will right themselves, others are possessed. It would be great if it was actually like the commercials, but its led me down the wrong path a few times when I forgot my regular meter.
I haven’t read the replies yet but wanted to just jump back on here to say WOW! I have NO IDEA how this could have happened but about 30 min after my reply to this issue the exact thing OP described happened to me BUT not a new sensor or transmitter. WOW. Well played universe. Currently my Dexcom is down.
This is crazy! Like it’s one thing to be experiencing this, but the irony of the timing is unreal.
Anyway, I wanted to send screenshots to show that this is NOT a new sensor, so that theory is out the window. And I just did a finger stick and I’m 153.