G6 makes me want to throw it out the window

Seriously. 80-100 points off about 50% of the time.
Just now, buzzing & alarming with URGENT LOW. Meter says 191. SERIOUSLY??
What the actual flipflopping fruitcakes am I doing wrong with this stupid thing?? I corrected it earlier because it told me I was 306…and meter showed 236. And yesterday, a similar situation.
I’m not new to Dexcom. But I’m seriously considering going back to the G4 if I can’t figure this ridiculous thing out.

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Covering the obligatory basics…it gets us all from time to time.

Calibrate when you have not eaten in 2 1/2 hours. You should not have taken any correction insulin within the last 4 1/2. Absolutely no calibrating when the arrow does not show steady behavior with the --> arrow. Do NOT over calibrate. If anything, when you see accuracy, consider calibrating even less than it requests that you do. If your numbers are roller coaster-ing a bit, it will be hard to get a good calibration. Check a manual sugar one hour before calibrating and if you check again immediately before calibration, it should be similar to the first check. If this doesn’t do it, consider checking the meter against a second one with different strips.

Some people will recommend sensor soaking the G6.

let us know…

I was in the same boat for the first few months with my G6 - almost went back to G5. After much patience and advise from this forum and Dexcom, I got things working. The things that made the biggest difference for me -

  1. soak the sensor (the most important for me)

  2. don’t over-calibrate. In addition to what @mohe0001 said, don’t calibrate unless there is at least a 30% difference between the G6 and finger stick. Make sure you wash and dry your hands before testing.

  3. use only very light pressure between the inserter and your skin when placing the sensor.

Sometimes I also have compression lows If I lay directly on the sensor at night.

Hang in there!


Yeah, definitely not having lows. Just struggling to stay in range with this humalog right now.
And actually I think I did soak this sensor…

I only calibrate when its that far off. 10 or even 20 points, I don’t bother to calibrate. But a consistent 80-100 points is super annoying.

Where are you wearing your sensor?

I found that I had to move away from the stomach areas I had been using with my G4. I moved out to my sides, then after about a month, I was able to go back and have excellent results.

Also based on a recommendation from one of Dexcom’s CDEs, I “pinch” a chunk of skin when I do the insertion. This helps get my sensor in the right place to read my interstitial fluid.

Maybe this doesn’t need clarification, but it’s not the points that it’s off, it’s the percentage. So, the 306 vs 236 is (I think) 29% off – not technically in calibration range. I totally hear you about being irritated by an 80 or more point difference, though. It feels totally wrong.

I’m a big advocate of not calibrating – especially during the first 24 hours of the sensor. I’ve experienced it going from reading too high to reading too low (or vice versa) and that’s a big pain. I don’t know about you, but I just find it viscerally alarming to see Urgent Low even when I know it’s wrong.

I also have the sense (not based on anything like a scientific examination) that when it’s off in the higher range it will get more accurate when it comes down to a lower range – or it could just feel that way because of percentages.

I’ve also experienced compression lows with the G6 – something that never happened with the G4 and G5 – no idea what changed that caused that, but that’s my biggest disappointment with the G6. I don’t like having to be aware of how I’m lying in bed. Otherwise, my experience with the G6 is positive, for what it’s worth (easier insertion, no calibration being the pluses for me).

Are you soaking the sensor? I had really annoying and recurrent false urgent low alerts during the first 12-24 session hours. Now I soak for about 12 hours before starting the session and the sensor is accurate right from the start.

I don’t soak, though it sounds like a good idea. Do you cover the soaking sensor with something to protect it and, if so, what?

I don’t, but others are using old transmitters (a bit tricky to get them out with the G6), or a piece of tape or a bandaid.

There are several detailed posts about this if you search, or maybe others will chime in.

I can’t remember where I heard it, but IIRC, for Medicare users there will be a means of switching back to the G5. I know that doesn’t help non-Medicare users, but thought I’d throw it out there. Does anyone remember such a discussion? It could have been a convo I had with Dexcom, or something online. Sorry my memory is so awful.

Given that our meters have a pretty high degree of inaccuracy and so does the CGM, I would first do a second finger-stick to validate the meter results and then if that closely matches, I would calibrate @ 29.66%

In a classic case of YDMV, my single biggest complaint with my G4 was getting compression lows. It got to the point where I was hugging a pillow every night to try and prevent them and some nights I just turned the CGM off - which to me defeats one of the main purposes of having a CGM with some hypo unawareness.

I have gotten a few compression lows, but I am finding them few and far between with my G6. Hoping you can get fewer of them, @Tnyc

It’s on my hip usually. I have to save my stomach sites for my omnipod, & even then, they’re getting flat worn out!
But like I said, lows aren’t generally my issue.

I am so very sorry you have having such a bad time with the G6 A! I love mine and have been using it with the Tandem IQ system since December of last year. I feel like I have given up some much control and feel so much freedom with this system!
In all this time, I lost one sensor and it happened when I calibrated. It was the only one I tried to calibrate. So my takeaway was not to calibrate.
And I am sorry to say, I really don’t know how accurate it is because I haven’t tested since before Christmas. I have learned over the years that the meters are probably not as accurate as we would like. How many times, same sample and different numbers? And for me with the pump doing it thing, I haven’t felt the need to check. It just shuts off and turns back on as the sensor tells it my sugar level. Most times it turns off around 83 and kicks back on around 90. In the 6 months using it, I have not had any lows that I couldn’t deal with and I don’t think I have been over 300 more than a handful of times.
So I guess my takeaway here is maybe just let go. Let it do it’s thing. I must say it has been very freeing not testing all the time. One less thing to think about or worry about.
I am so sorry you are having such a hard time with the new system. But I see the Dexcom people at my workplace once in awhile and I just go on and on about how much I love the new system! Hope you can find a safe spot!


I do a meter check as soon as the 2 hr warm up is completed to get a ballpark idea. Then another meter check after 12 hrs.

A good G6 sensor for us will be within 10 points after the initial 12 hours. At any range. I accept a max 20 point spread. More than a 20 point spread after 12 hours and I will calibrate.

I expect significantly greater accuracy than 30/30.
IMHO it is not practical to expect any sort of usable results with an automated algorithm such as the Basal-IQ if your sensor is barely within the 30/30 specs.

BTW - Dexcom definitions of the 20/20 and 30/30 rule.

G5: 20/20 rule:

  • If the meter shows 80 or less, CGM should read within ± 20 points.
  • If the meter shows 80 or above, the CGM should read ± 20%.

G6: 30/30 rule:

  • If the meter shows 70 or less, CGM should read within ± 30 points.
  • If the meter shows above 70, the CGM should read ± 30%.

Well, in a fun twist of events, my sensor got ripped off last night which rarely happens and of course Dexcom is delayed sending out my order. And that was my last sensor that I’d planned on restarting…

My G6 was way off too. I finally gave up on it and went back to the G5 for a couple of months, then switched back and the numbers were more accurate. I still calibrate everyday. At one point, I was wearing both a G5 and 6 for comparison purposes. G5 was preferred. I never heard of sensor soaking. What? I will have to search that. I also found when I called Dex tech support, they were very helpful and so far, I think they have sent me half dozen sensors to replace the problem sensors I have had that lost the signal for more than 3 hrs or were just way too inaccurate. Using less pressure on the sensor installation is also an interesting idea. I prob. press too hard. Mine are all on abs, pod placements are always on my arms. Omnipod.

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I had a Libre first and then switched to the Dexcom. I honestly did not think there was a huge difference between the Libre and the Dexcom. I do wear my Dexcom on my arm.

The Libre was always off, but it usually was consistently off the same amount so I could adjust for the difference when dosing. And I’m huge into I don’t do finger sticks for days or even longer with any CGM.

The Dexcom won out because of it’s ability to calibrate and the alarms. The alarms still can be annoying, but I have learned to turn most off or set higher numbers at night so they don’t wake me. ( I have dawn phenomenon I choose to sleep through) I used to overlap and wear 2 Libre sensors on it’s first 12 hours and have found for me that the Dexcom is pretty good in about 2-4 hours.

I want my Dexcom within 5 points at anything under 120. So I do keep calibrating mine until it does read accurately. If it varies a little bit at my random checks, that’s ok. I don’t care as much about higher numbers as since I’m too high I have to drop anyway so oh well.

But when I calibrate, I’ll wait a couple of hours for a sideways consistent arrow at least about 30-60 minutes. I’ll do a fingerstick, then I set the timer for 5 minutes, then another 5 minutes and then if needed another 5 minutes and if it falls within about 5 points at one of those points I’m happy . I do not believe in the percentage thing being what you judge by, they tried to tell me that 30% was acceptable when I called and me being 69 and the meter saying 92 was supposed to be okay? Uh no way. Same thing meter saying I’m 120 and a finger stick saying I was 150 and that was supposed to be okay, NO! Dosing or not dosing at 120 is far different than what I would do at 150. I calibrated it a few times and they replaced it because it froze. These things aren’t cheap, the Libre is cheaper, if they aren’t going to be accurate because of calibration why not the cheaper Libre with an ap for alarms? (the Libre is going to be adding an alarm I think within a couple of years)

But I found the biggest help is wearing the sensors the longest time possible. Because I wouldn’t be keeping it on if it wasn’t close, it’s already well soaked and while I still maybe have to calibrate it a couple times the first day, I just can keep ignoring checking it for days on end or even until the next restart! I’m working on my 3rd one over 20 days, keeping it on my arm for that long is the trickiest part!!! And by the 20 days of repeated skin tac adding it does start to look grungy around the edges,.

Yeah i don’t calibrate it at all unless its off by those 80-100 points. And when i do, it tells me to wait 15 minutes and calibrate again. And i’ve even had it tell me that a second time! So i need to do 3 fingersticks within an hour for a device that claims no fingersticks?? Yeah right.

To me it seems like the 2 hour warm up period should be enough time for a new sensor to soak, but clearly what do i know? I did have good results for several days when i restarted a sensor but then when it did go bad, it went downhill FAST lol.

I might be having some life/insurance changes here soon so no telling if i’ll even be able to afford to stay with dexcom. My current insurance will only approve a 30 day supply at a time. which i need to call and fuss them out about - after all, its not like my diabetes is going to magically clear up anytime soon! And with the “10 day delay” on new sensors, plus shipping time, i’m basically missing almost 2 months worth of blood sugar data over the course of a year.

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I would encourage you to call the Dex Tech support line and then ask to speak with one of their CDEs.

For me, they provided me with some logistical info that was more in line with actually living with this device attached. By no means was the advice perfect, but it helped me understand the things I needed to do a bit differently, because the way the sensor works on the G6 is different than the earlier models.


I think you need to finger stick. I could give myself the same advice…I dont always do it when I should. But, try calibrating when the finger sticks are very close to one another over the course of an hour or two. If you have taken insulin recently, or eaten, it may get messed up.

I would think very carefully about staying on a pump without a CGM. I think that gets dangerous.