G6 1st 24hrs exaggerates lows, like a LOT

THIS is why I keep wanting to roll my sensor over to a new session rather than replacing it. I hit day 21 this a.m. and looking at the ugly mess of peeling tape-overs I decided screw it I’ll just break down and put on a new one. It was still accurate, but it was about to fall off and at some point you have to accept that you can’t fight adhesive erosion for ever. So I did it, and all goes well, pretty much until lunchtime pre-bolus, which starts doing what it’s supposed to: get me set on a down curve before the carbs kick in. But down and down and DOWN goes the CGM curve, and soon I’m getting URGENT LOW, 48 with a down arrow, and I know it’s not correct but I test anyway. Partly so my office mates won’t come rushing in thinking I’m dying. Sure enough, fingerstick: 91. “Don’t over calibrate!” warnings ringing in my ears but this is so far wrong. So I finally entered a calibration, hoping it’s not going to boot me off with one of those error-checking interludes. So far so good.

But dang—I know the first 24 hrs can be flaky but when I first upgraded to G6 I had very little of that, not really any different from G5. Now it seems like my last 2-3 sensors have all gone crackers at the start, and it’s always exaggerated lows in this initial period. I know it will settle down to its usual very high accuracy, but until then it’s almost useless. Guess I may just have to break down and try the “pre-soak” thing, but honestly I really hate adding another complication to the process of sensor replacement. Whole point of the G6 is to make that process easier, isn’t it?


We are in the last week of our G5 transmitter!!! I do not want to change to G6 yet; it seems nothing has improved since we tried it back in October. :roll_eyes::unamused::worried:


I dunno. I’ve mostly had a really great experience with it. It’s just this first 24 hours thing. And I really shouldn’t whine, given that I’m regularly getting 20 days out of each sensor. But overall it’s super accurate, the business of not having to enter a calibration at the end of the warm-up turns out to be a much bigger deal for me than I thought it was going to be, likewise the other features I didn’t think so much of before I switched, like the low-profile transmitter and easy one-click inserter. But mainly it’s the greatly improved accuracy and greater sensor longevity. After 36 yrs T1, it’s not easy to give up finger-sticks entirely but I’m down to one or two a day and regularly bolusing off my CGM reading, which I never quite trusted for that with the G5.


Almost every successful tactic I use, when first tried, felt aggravating that I had to add yet another step to my diabetes management. But then the tactic improves my life and I accept the additional step. With several successful iterations, the new process doesn’t seem that onerous and the habit gets rolled into the new routine.

I don’t have access to the G6 yet and have been content to hang back with the G4 system. I started with the 7+ system back in 2009 and every version I’ve used has had its inaccuracies.

Early this morning, my CGM woke me up with a low alarm bordering on an urgent low. Instead to getting up to poke my finger and ruin my sleep momentum, I just ate 1/2 of a glucose tab and tried to go back to sleep. I couldn’t fall asleep again.

When I did get up, I noticed that the “low” that woke me up was likely a compression low probably cause by me rolling over onto the sensor. here’s that trace.


I’m taking delivery of a G5 system any day now. I used the G5 a few years back but didn’t like several things about it, particularly the background white on the receiver display that irritates my night vision.

The CGM data is so valuable that I’m willing to put up with some irritation.

I hope your pre-soaking helps.

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Presoak is really the key for me. If I don’t do it, the first 24 hours are a nightmare. Presoaking is a bit of a hassle, but not too bad in my book given the advantages I get using the G6 - especially Basal-IQ with my X2.

The main issue I have with presoak is predicting when the sensor in current use is going to fail. I extend my sensors past 10 days and they have been lasting me another 3-5 days. But it’s hard to predict when it’s going to die. If I guess wrong and the sensor fails before I presoak another, I’m stuck with no CGM data during the presoak or I have to start a new sensor without the presoak and endure the bad data during the 1st 24 hours. So now I’m playing very conservative with sensor extension. I change it at day 3 of the extension.


There was a recent minor change to the G6 transmitter. I am unsure if it was an improvement. One certainly hopes that would have been the intent.

The new transmitter is still on our shelf so we have no first hand experience with it (yet) to see if we notice any differences.

Our newer transmitter has a serial number of 81xxxx vs 80xxxx for the previous G6.
Also our newer transmitter has a manufacture date (funny broken line symbol) of April 24, 2019 which I believe was the first date the newer ones are manufactured. Both the date and serial number are reasonable guesses on my part in terms of identifying the G6 Transmitter which incorporates the minor firmware change.


The presoak works for me.
I change my sensors on Sunday mornings, and I run my sensors for 14 days. I don’t want to mess with tape, etc. to extend another week, so it isn’t worth the hassle for me at this point.
I skintac, let dry a bit then insert new sensor at night before bed.
First thing in the morning I swap the sensor over and usually either go back to bed or sit and have coffee.
This is now my routine. Unless I have a failure of the adhesion before sunday, I don’t plan on changing it.
Btw, I don’t bother putting in a dead transmitter, putting tape over it, etc. I just put the sensor on an ignore it until morning. No issues to date.


Same for me.

Interesting! I just looked at the serial number for the transmitter I installed for my current session. It has an 81xxxx serial number. I haven’t noticed any differences so far.

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@Paytone - You mentioned you typically extend by 3 days.
It would be interesting to know if your extension process still works the same?

Also if you still have the box was your G6 - 81xxxx manufactured on or after April 24 of this year?

I’m due to extend on Friday. I’ll share what happens.

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@Tim35 I let xdrip preemptively restart my sensor. Works perfectly for me, no issues what so ever. I rarely even pay attention to it anymore.

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@Hammer - Same question. Does it work the same on the revised G6 transmitter?

My current one is an 81XXXX also, started on May 5.

All I have to say is SOAK the sensor for a full day.

Good to know. I hate hassling over that little stuff. Anyway, the sensor filament isn’t a cannula—it’s not like germs can crawl down into it if you don’t have a transmitter covering it. As long as the contacts are clean there shouldn’t be an issue.

I’ve been running my sensors for 20 full days just b/c I’m lazy about changing 'em, and anyway if they’re still giving good data it seems like a waste. I use the SkinTac method, making sure to give it a bit of time to dry before inserting the sensor. For a while there it seemed like I was getting nearly the full 20 days before the original adhesive patch started to peel, but more recently they don’t seem to be lasting nearly as long. Same goes for the GifGrip patches I’ve been resorting to—seems like they used to last longer too. Must be me! Warmer weather, more exercise? Dunno. :man_shrugging:

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Not sure, the VA is taking forever to send me my replacement sensors.

Have you tried the Dexcom overpatches you can get from Dex Tech Support?
We have been using those and they REALLY stay on.
Although we can not run as long as you can.
All our sensors do not even make it 10 days and if extend, we can only get 2 or 3 days longer. But not due to the adhesive - for us. It is something else that just makes the data start being bad. sensor/body/chemistry/immune/whatever/something

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Sorry to hijack this thread but I am relatively new to this (6 year old daughter diagnosed in January).

is there anywhere I can learn how to extend the G6 sensors? mine kicks us out after 10 days, in fact some don’t even last that long…

Also, what is this “presoak” thing you guys are mentioning?

Thanks in advance for any tips you guys might have.

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Here’s a post about extending a G6 sensor:

Note that step 5 specifies “without code” but you can actually enter your old sensor’s code number at that point. So I always take a picture with my phone whenever I start a new sensor so I have the code handy when I roll it over.

Basically the idea is to insert a new sensor ~24hrs before the current one runs out. This gives it a longer acclimation period than the statutory 2hr warm up. By most accounts this helps keep the new sensor from being so erratic at the start of a session.

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No, I didn’t know they were offering anything like that. I’ll definitely check it out.

Yes, this is apparently a thing. Medtronic Guardian 3 users struggle with it a lot, particularly since the stated sensor life is only 6-7 days to begin with—sensors going erratic after just a couple of days. At least one person I read said that Medtronic techs told them it was an individual physiology issue as you suggest. I didn’t have any such problem when I was on the 670G, but I see a lot more discussions and complaints about it in those threads than I’ve encountered in Dexcom ones.