A weird thing about the G6

So I upgraded to the G6 about 3 months ago and I think I’ve had it long enough to say that this is a repeated pattern, i.e., a thing.

Namely, that when I roll a sensor over to a second session, I get the same slightly erratic behavior in the first 12-24hrs as I do when I start a genuinely new sensor. For most of both sessions, initial and rollover, I’m finding these things remarkably accurate, or at least in remarkably close agreement with my CounterNext+. And every time I start a new sensor, the G6 is a little flaky, just as it was with the G5. Only unlike the G5, it’s also a little flaky every time I rollover to a new session with the same sensor.

Yesterday I did a rollover and suddenly it kept drifting up into false highs, would come down if I did a calibration (washed hands, did the finger stick twice just to check), then start drifting back up again, then suddenly drop—all the kinds of things you get if you’ve genuinely changed sensors, except I hadn’t. I was at the point today of thinking I should just give up and insert a new sensor, but then it settled down and has been exemplary every since, including when I was in an exercise-induced low—something the G6 seems to track much more reliably than the G5.

Don’t think this ever happened with the G5—once it was locked in it behaved the same all the way to the end of the second session. Not as accurate as the G6, but nothing noticeably weird in the first 12 hours or so of the second session. I’ve only done the rollover thing now with the G6 three or four times because the sessions are longer, but I’m pretty sure I’ve noticed this every time.

Has anyone else experienced this with a G6?

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Which method are you using to restart ?

Standard dexcom receiver or app, or xDrip?

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Yes. I have the same. But the restart wonkiness is only a few hours instead of a whole day. I “soak” my new sensors for 3-6 hours before starting and that seems to help the initial start. Here is my restart method:

-Wait until my sensor expires.

-Start session and choose NO CODE

-Set timer for 15 minutes and let session ‘warm up’ for the 15 minutes.

-Stop session

-Start session WITH the code of the current sensor I’m wearing. (I take a photo of the code whenever I insert a sensor so I don’t lose the code).

-It will take 2 hours to warm up.

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I haven’t seen it yet, but I have a theory on what might explain at least some of this.

Unlike the G5, the G6 contains a calibration file so it doesn’t require manual calibration. The calibration file isn’t a static curve. It changes over the life of the session anticipating changes in the sensor and the surrounding tissue. Most of the changes occur in the first few hours as the site stabilizes. After that the changes are much smaller and consistent for the rest of the session. All that is from Dexcom’s G6 patents.

The rest of this is based on my assumptions:

I believe there can be significant differences in initial stabilization between different sites and different people. The fixed sensor calibration can’t account for this. That’s why some of us experience such erratic results in the first hours of a session. Now move on to a restart situation. The site is already stable but the calibration file is expecting dramatic changes that happen with a new sensor. Once again there’s a mismatch, hence the strange results.

This can’t be the full picture. It doesn’t explain why this isn’t happening to all of us when we restart. It should also happen when we ‘soak’ a sensor until the site is stable, then start the session. Most of us don’t see it. But I think this idea point in the right direction.

One way to check this out might be a restart with no calibration code. Now the system runs based on user input - similar to the G5.

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Do you think they are ‘stretching’ the hardware/software with an increasing number of models/functionality? I feel like my G4 is working fine again. But, maybe between the three models, some things are functioning a little less optimally. I’m not one who has ever had much ‘flaky’ sensor behavior. It makes me nervous. I’m afraid that I have been on the sensor so long, I have become sensor dependent. I think erratic readings would cause me problems. Especially, if I didn’t expect them. Have you had any problems in that unstable 12-24 hour period? How do you guys deal with that? Its predictable, so you just do more manual checks?


I’m using the App method posted by @Aaron2 (thanks Aaron!), with the substitute step 5 where you add the sensor code (because you’ve thoughtfully taken a pic of it with your cellphone when you did the original insertion).


Yes, same method I use. Except the “soak” thing. Maybe I’ll try that next time.

Yeah, I was wondering if it was something like that. I haven’t really delved as deeply into the specs and details on the new system, but I had the impression there was something like that going on—that it would have something to do with the particulars of how they’ve improved the algorithms for accuracy and the “no calibration” capability.

I’ve heard the same thing. It does make some sense based on with G5 the first day was really bad for accuracy where with G6 the first day is much more accurate.

This is useful to know. Unfortunately, Caleb’s sensors often flake out and fail before ten days elapse.

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is he thin?

Another option is to remove transmitter from sensor, wait a few minutes, then put back on. This may work better as it may trick transmitter into thinking new insertion, and adapt with code differently. There is another topic with youtube video on how this is done, using a contour next bg strip to release the tabs that hold transmitter in.

I have used the 2 hour restart, with receiver in microwave during 2 hr warmup. With xDrip, I continued to get good readings. After 2 hours, G6 receiver picked up readings fine, matching xDrip.
(May be different results using phone with G6 app.)

Must be a reason to put G6 receiver in MW, that prevents communication with transmitter during that time.

Caleb? Yes, he is lean.

i don’t remember if you have been told by Dexcom (as I was) that leaner patients have more issues with G6 accuracy than they will have on the G5. ie, they admitted to me that the G6 is problematic for those with lower BMI’s.

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That is news to me! Interesting, thanks.

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I’ve had quite a few convos with Dexcom over the last 18 months, and I ask lots of questions, so that may be why I learned about the BMI issue and you didn’t. WHenever I call, I try to learn a thing or two. I’ve been that way my whole life and I’m sure I might have driven some teachers crazy, but I don’t care. I like to learn! :slight_smile:

I tried that Thursday evening and it worked well, although I was using the One Touch test strip tool :wink:. It really took some doing because the site was on my rear flank and hard to reach. I almost pulled the sensor out, but now that I have the technique I think it will be easier.

I’m 99% certain the transmitter thinks it’s a new sensor regardless of the restart method. And actually it would be better if it thought it was a continuation of the current session. Then it wouldn’t start comparing the very stable-sensor output with the rapidly changing ‘new session’ portion of the calibration file. I think that’s responsible or the strange results after restart.

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Buddy System !!!

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Very good point! Unfortunately in this instance my ‘buddy’ was fast asleep and I’d pay dearly for waking her up. If it was anything tougher than a test strip she might draw blood :grin: