And in an ultimate act of punishment, I bumped up against the door coming into the house and dislodged the sensor. So I am honored to get a single day out of my first sensor. Hopefully I get more days out of the next sensors.
Are you considering changing your name to āClouseauā? 
I inserted a new sensor today and it was spot-on from the get-go. Within a couple of points of my BG meter for the first 8 hours. I predict that I will not see any blood when I eventually pull the sensor. Sensors donāt seem to tolerate blood well. The inconsistency of sensors is a major frustration. I would pay double if all my sensors were as good as this one. I expect that the next breakthrough will be a non-invasive sensor. I donāt see how an invasive technology that is so vulnerable to blood can ever be reliable.
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By all means, call Dexcom and tell them that you dislodged the first sensor ā theyāll probably replace it (though theyāll want to hear that it was located on your abdomenā¦) Iāve had a few failed sensors lately because of the heat and sweating - they get replaced.
For convenience, I usually insert new sensors in the evening; however, they do tend to be less accurate the first 12 hours or so ā especially on the low side. That first night, I do try and be sure to double-check lows with a fingerstick before correcting it, especially if I donāt feel symptoms. I donāt always feel lows, so I donāt want to ignore the warnings, but I have had more false alarms on the low side the first night after inserting a new sensor.
The other time I have to be careful is when Iām dehydrated - after a lot of exercise or many mornings when I awake. I find that drinking some water and waiting 10-15 minutes avoids that problem ā again, the Dexcom usually errs on the low side in that case.
I find the first 12 hours, especially, more inaccurate. During that time, I always test before making treatment decisions. But after that the accuracy usually improves. My guess is that the Dexcom needs a few callibrations to really get going.
Iāve been scared to use my arm for sensors because I pay for all of them, and Iām scared of dislodging one as you did. I got brave and put my most recent sensor in my arm, but I used the back/inside of my arm, so itās closer to my body. Iāve brushed against doors and the sensor is protected. Also, my arm so far has been extremely good in terms of sensor lifeāmy sensor is now on day 25 and has not had any periods of ???. If it lasts two more days, itāll officially be the lonest sensor Iāve ever had.
I agree with the suggestions to keep your testing stuff by your bed. I have one set upstairs and one downstairs and another in my purse. I would take the lows seriouslyā¦ I have been flatlining sometimes it appears- and when I test, some confirmed, some were higher but I had some where dex showed me straight arrow up at 47 and the finger stick wasnāt far off. So my liver was raising bg while I slept and even if the finger stick is higher you can still have been quite low.
Everyoneās comment about keeping testing supplies right next to the bed are absolutely right. I admit, I have neglected this. And while I have had reasons I have placed myself at some risk. I had woken myself to test at night, at the request of my endo and done this perhaps several dozen times. I never observed any hypos. And I also suffer from disturbed sleep (sleep apnea) and sleep with a CPAP. I donāt awake at all and if I do awake it can cause me to lose several hours of sleep. So I justified not testing overnight and stopped bothering with keeping my testing supplies.
So I will mend my ways and put a meter in the drawer by my bed along with my smarties. But at least now with the CGM I will hopefully have a better first line defense to detect any hypos.
ps. In the two nights since I have been flat all night, so I suspect it was just a āwonkyā reading.
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I frequently found the Dexcom 7+ to give wonky readings when I laid down regardless of how long that sensor had been runningā¦ They were usually disproven by meter checks. I never got a good explanation for why this was happening, but getting horizontal frequently caused the Dexcom to falsely read plummeting lows that were not actually happeningā¦ Large part of the reason j decided cgm wasnāt for me
Putting pressure on the sensor (such as lying on it or against it) can cause false lows. I get them sometimes, but not too often. The other day my sensor had an off period where it said I was 2.2 for half an hour and then started rising rapidly until it said I was 19.4 with a double up arrow. I calibrated it twice and it sorted itself out (itās also well past one week, so Iām glad it recovered!).
I have a very busy side of my bed, too. CPAP machine, BG meter, insulin pump, CGM, glasses and book Iām currently reading. The CPAP machine was a wonderful addition a few years ago. I did get a good laugh when I explained WHY I needed a CPAP machine to some bandmates.
ā(The back of) my mouth is too small.ā This had them rolling with laughter.
Usually G5 provides extremely useful and actionable information. Only occosionally during the first 24 hours will there be a large variance. Whether itās in the first 24 hours or any other time, we use CGM information as part of the equation - what else do we know? Is Caleb symptomatic? Is there a reason to expect him to be out of range? And judgmentally confirm with a fingerstick. I like @Helmutās approach and description - tries to predict what the reading will be. I agree that a different number on a meter than the CGM does not necessarily mean there is a variance either bc BG is constantly changing and Dexcom may need a minute or two to catch up, or bc meters are not as accurate as we sometimes believe.
As far as knocking the sensor off, I think itās something you get used to - at first you have to think about it and then you compensate for doorways and such without thinking about it. Iāve worn both Dexcom sensors and OmniPod and knocked into things, and then found myself compensating without realizing it until after the fact.
Well, I got another sudden drop last night on the sensor I put in on Saturday. I dropped down into the 50s and it alarmed.
This time I was prepared (thanks to everyone for the suggestions to keep a meter next to bed) and took two readings from my meter 124 mg/dl and 125 mg/dl. In the next few minutes the Dexcom gave another reading suggesting I was up in the 70s and then I got the dreaded ??? It may have been that I was sleeping on top of the transmitter. Anyway I ended up rolling over and just going back to sleep and after about an hour it came back on-line and showed me flat for the rest of the night (although higher than average).
If this pattern repeats Iām going to call Dexcom.
Weāre you by chance laying on it or pressure being applied to the senor. That can cause wonky readings.
The answer is yes, and this will be a usability issue for me.
This pattern is exactly what my Dexcom
Did Iād say 3 times / weekā¦
Theyāll send you a new sensor, go over your insertion technique, which I imagine youāre already doing correctly, tell you not to take acetaminophenā¦ The new sensor will do exactly the same thingā¦
Iāve found compression-induced false lows while sleeping to be only an occasional nuisance. The biggest risk Iāve found is acting on this bad info in an attempt to go back to sleep quickly. I usually side-sleep and I try to install my sensor where it minimizes the risk for sleep compression. The classic ādeep-Vā signature of compression lows is the tell-tale mark.
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These patterns plagued me even when ensuring there was no compression, if put the sensor on my stomach and never sleep on my stomach but still encountered this often
I do the same, @Terry4, though I go a step further and try and sleep only on the side that does not have the sensor (with a fair bit of success). Iāve managed other sleep-position-related issues by consciously altering my sleep position through the years, so Iāve gotten good at this 
.
The other tell-tale sign of compression lows is that the receiver often goes to ??? or signal lost shortly after the the false low.
That said, I think Iāve only had one such false low in the last 3 months that I can recall. Of course, though, that one time, I was too tired and too lazy to back up the Dexcom with my meter and ended up fairly badly over-treating a non-existent problem (183 on wakingā¦ oops!).
Your experience combined with some others tells me that the CGM does not work for everyone equally well. Iāve luckily found the CGM to be much more useful than the nuisance it sometimes causes.
That being said, Iāve also found a close to 100% association with a poorly performing sensor and evidence of blood, dried and otherwise, when I removed the offending sensor. In a yearās time, I probably bail early, like on day 1 or 2, on 2-3 sensors. Sometimes I report them to Dexcom for replacement; sometimes I donāt. I get more than 7 days on almost every sensor so I just write it off with the balance solidly in my favor.
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I also decided that it was directly in my own worst-interest to walk around with a device on my body constantly recording false lows when it comes time to grant the bureaucrats (who renew my professional license) access to my medical recordsā¦ So I decided it wasnāt for me. Havenāt missed it, but have considered intermittent short-term use when it seems there are new lessons to learnā¦