Dexcom G6 Sensor Issues

I recently was given a Dexcom G6 trial from my Endo’s office and upon setting up the initial sensor & transmitter, I had instant issues post-warmup.

I had my iPhone XS Max well within 20 feet of my sensor, I made sure I had it in an optimal spot on my abdomen, and I called tech support about an hour after I noticed I was having signal loss issues. When I didn’t have signal loss issues, I had repeated 40mg/dl “severe low” alerts when I was really 132mg/dl and 123mg/dl.

The first tech support call suggested I calibrate 3 times at 15 min. intervals and that it should correct itself, it didn’t. I then was receiving high readings of 234mg/dl and upon checking with my finger sticks I was a healthy 170mg/dl. I began to lose signal AGAIN (ughhhh, what the hell. SO frustrating… esp. for a beginner) so I made one last call to tech support. He asked me if I calibrated, I said yes. (Later, I did some reading and apparently you’re NEVER to calibrate a new sensor? What’s the actual rule-of-thumb here, then? Any insight on this would be great as I am still learning the CGM way) After this, he quickly explained he was putting in an order for a replacement sensor and that I should remove the current one and wait 3-5 days to receive the new one in the mail. :worried: after I had removed the sensor I: A.) Read online that you may experience fluctuation in the first 24 hours of using the sensor… well crap, I already removed it as tech support insisted. B.) Am unsure if tech support’s initial call may have absolutely thrown off my sensor due to their suggesting I calibrate a brand new sensor… and C.) I have iOS 14.6 running and I’m seeing on the website the G6 app is compatible up to IOS 14.4.1 - could this have been my issue?

Any opinions on this matter would be greatly appreciated, as CGM devices seem to be alllll greek to me.


Sounds like you had a faulty sensor! Yes, the sensors can have accuracy issues in the first 24 hours but yours were really extreme. Many of us use the no-code mode and also insert a new sensor several hours before doing the sensor warm-up. I have found this helps a lot!

ETA: I usually receive replacement sensors within 2-3 days.


Using the code and never calibrating it works well for some people. For others, it does not work as well.

I never got good results using the code, so I do not use the code anymore. It’s been much better for me with calibrations instead.

I think the key is - if you use the code when you start it, and your numbers are way off, it might be better to NOT use the code and just do the calibration instead.

The numbers you describe sound like you might want to try skipping the code next time and seeing if it works better that way.

  • Test different sensors both ways - using the code and never calibrating it, and then on a different sensor, not using the code and calibrating it.

I think the consensus around here is that you should either use the code and never calibrate, or skip the code and calibrate. But using the code AND calibrating it will give crappy readings. :man_shrugging:


@Eric So what you mean to tell me is that I’m right and tech support gave me terrible advice? Shocker. :joy: :joy:


Thank you @CatLady I’ll try no-code and calibrate once my new sensor arrives. That would be my luck though, on the first try having a faulty sensor. :sweat_smile:


Well you are in the right place now, here at FUD. The info here is better than anything you can get from any of the support people, and probably from any medical team. :+1:


@Eric I couldn’t agree with you more!


@Necroplasm , there is also an online tech support for for Dexcom:



@CatLady I will bookmark this, ty! I’m sure I’d rather come here for advice in the future though. :laughing:


You can also submit a sensor replacement request online at the link Catlady posted. It’s much faster than calling! I had to request one for my failed sensor today :frowning:


@Trying I received a confirmation email from Dexcom shortly after tech support put in the request for me, thankfully. I should receive it in the next 3-5 days. I’ll be more careful with how I set this sensor up for sure. It’s tough being a newbie with all this stuff.

Good luck with your replacement sensor! May the odds be ever in your favor. :joy:


I would have left it in to see if it corrected itself within a day or so. That usually works for me. (The worst one took me until day 3 to become fully reliable, but within 24 hours usually they’re pretty good.) I’m in the never calibrate bunch, but others are happier with no code and calibration. You’ll have to try it both ways to see which is best for you. And I support CatLady’s suggestion to insert a new sensor several hours before the old one expires — it can help in getting past the initial poor accuracy.


I will note this down for future reference, ty! Unfortunately, I was so new to this whole CGM world that I actually listened to tech support sigh. I’m honestly feeling a lot more at ease about the new one arriving because I’ve received a lot of good intel here from everyone!

The only thing I’m worried of now is the fact that I’m a bit of a rough sleeper… though I’ve read on other T1 discussion groups that pulling it out or bumping it is usually one of the biggest fears a newbie has. Anyone else toss and turn a lot at night? Are my fears irrational or should I be worried? lol.


I think it’s difficult to pull a sensor off by only using a mattress or pillow. Might be a fun FUD challenge! :grinning:

If it’s on your arm, it might get knocked off by a door frame. I’ve done that. And after it was on for 10 days and the adhesive was wearing out, I’ve had some fall off during the day. And I’ve had some get caught on a shirt when dressing or undressing, and I just pulled it off.

But never from my mattress.

It might be more likely for it to come out for you in certain circumstances compared to others. These things are somewhat unique to the individual based on where you put it and all of that stuff. It takes time to figure out what works best. If you sleep crazy, it might come off if you have it on a certain place.

Try wearing it in different places. See which places work best, which ones are more accurate, which ones stay on, etc.

For example, I sometimes wear my omnipod on my arm. It makes it easy to have it there for when I go through airport security. Like I don’t want it on my butt if airport security is going to check to see that it’s not an explosive device! :open_mouth:

So when I am traveling, it goes on my arm.

But if I am going to be in packed crowd, I want it on the inside of my arm instead of the outside, because it will be less likely to get knocked off by someone walking past.

Experience is a painful teacher, but it’s the best teacher we have.


The thing to watch out for is a compression low, which can happen if you end up sleeping on the sensor, e.g., when it’s on the outside of your arm. When a steep drop like that occurs, do a fingerstick right away to verify!


That’s what I’ve read in some discussions, so I will try and be super mindful of where I put my new sensor. Which to my excitement should be arriving tomorrow by end of day via FedEx!!! So excited to get the ball rolling on this as I want to get a full view of how my BG fluctuates throughout the day.

Also got a notification from my pharmacy that the sensors are not covered - NOT surprised! I’m thankful for my Endo office, they have already put in the footwork with a DME corporation that specializes in finding medical supply stores that will cover my needs. It may take awhile, but I’m so relieved to know that they are working on it for me. Especially since the sensor that’s arriving is essentially the only one I currently own lol.


If you get in a pinch, give me a shout, we have a few extra lying around.


That’s so kind of you! I will definitely keep that in mind if I have any future issues with coverage. It’s just such a shame that even when you have an official diagnosis of T1, they still don’t want to cover any of the things you need sigh. 'Murrica.


For me the compression low is no more than a minor nuisance. I’ll get a low alert, look at the Dex graph and see that a normal level trend suddenly dove straight down. That had to be a compression low because I haven’t been taking a bolus in my sleep, so there’s no way my BG would abruptly plummet for no reason. I just change body position and go back to sleep.

You could experiment during the daytime, intentionally causing a compression low to see how susceptible you are and what it looks like on the graph.


Only a 5 point difference in just the 4 hours, and about 2 hours post warm-up. Ahhhh, sweet relief!! I can relax and enjoy the G6 now.