Just so many Dexcom G6 fails lately

I have been using the Dexcom G6 for about 4 years now with almost not a single issue.
Since February 2023 I have had so many problems. This morning alone two sensors failed to detach from the applicator and the needle didn’t retract- getting stuck in my skin with adhesive attached. Then the third one warmed up to a startling reading of 246 with two arrows rising. A finger stick showed a reading of 134. problems have been things like sensor readings 50-70 points off in the middle of a 10 day session, the app says one number and the pump says another, and the already mentioned applicator issues. More than once I have had readings of 80 with an arrow or two straight down only to confirm with the meter and it’s actually 40+ higher. I have called in about 12 replacements since mid February.
The last call to support told me I should look for a new system as my body “obviously doesn’t work with the G6”. So they blamed it on me. I know there is a 30 point accuracy spread and I never treat without confirming. But its scary to have this happening when I use a Tslim that doses or withholds basal depending on the readings. Anyone else having issues like this recently?


Hi @Spooky welcome to Type One Nation. No not really. The g6 for me is a little off the first 24 hours so I don’t even bother until at least the first overnight. After that it has been very predictable. Every time I’ve e ever had any kind of problem, Dexcom just sends a new one. Sorry about your recent troubles.

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@Spooky Sorry to hear you’re going thru the issues of late. I’ve read a number of people having issues the last year. It may be helpful to monitor/report what the lot/series #, Manufacturer date, etc. and possibly avoid those in the future. I did this on a batch of three I had issues with and Dexcom replace the entire set with a different lot. Hard to believe you can use the thing for a long period of time and suddenly its “your body” that’s the problem, unless you started/stopped taking certain meds or eating a different diet (I doubt the latter would be an issue). Please let us all know how it turns out with Dexcom or your further experience; we can all learn from each other’s experiences.

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Thank you. yes I am doing that. I will let you know. I have noticed most of the failures have been with the replacements they send

That sounds so frustrating. I’m so sorry that’s happening. I have been using G6 with Omnipod for 7 months. I’ve had very good luck. I do double check the first day with finger stick readings and a few times it’s been way off, so I calibrate and that seems to take care of it. Luckily I haven’t had application issues.
Thinking of you and hoping this gets resolved.

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I’m a cynical old man, but i wonder if it’s anything to do with the fact that the ONE came out last year, which is based on thr same hardware. Like the OP, I used the G6 for 4 years and never had a problem with it. I switched to the ONE late last year as it’s funded by the NHS in the UK. The qualityt of the ONE was really poor - I had a 50% failure rate on the sensors and MARDS of 30%.
I’ve since moved to the G7, (which I have to self-fund) and it’s absolutely brilliant. SOO mucy better that the ONE, and even better than the G6, at least for me.
Good luck!


How are things going with the Dexcom accuracy? I’m really interested since I’m considering getting it soon. I’ll use it until G7 is paired with TSlim. So, it’s important for the numbers to be accurate since the pump relies on that for my doses. What you describe is very disturbing.

Hi @HighHopes Dee - the G7 is a revelation for me. Warm up time is 30 minutes and every one I’ve used so far has been percet straight away - MARDS of less than 5% compared to my Accu-Check instant meter.
I would hope that the G6 is more reliable than the ONE - the G6 was certainly fine for me. It is a worry though. Here in the UK the ONE is the model that can be precribed by GPs so it’s effectively free for some people. It would be concerning if you had to pay for something that is accurate. The G7 is costing me GBP150 a month, but I think it’s worth it for the peace of mind. I’m very lukcy that I can afford it though, not everyone is able to.


Rod, that’s good to know. I used Dexcom years ago, before I got a pump, Then, it was about the same as my Medtronic Guardian, as long as it was on my outer, upper arm.

I find it really fluctuates Dexcom says a 30 point difference is still considered accurate 30 points is a lot when the CGM says 110 and I am really reading 80 with a finger stick. The other day the CGM said 130 and wanted me to bolus when a finger stick said 100 which didn’t require a bolus. I am hoping the G7 is more accurate. I have used the G6 for a little more than 4 years and haven’t had any issues besides out of range alerts when the pump and phone app are right near me (attached lol) at all times. I was also told by someone at Tandem that they are in negotiations to use another CGM. Wonder which one? Libre?

All CGM, all of them, do not measure blood sugar directly. CGM reads interstitial fluid. The composition of the interstitial fluid changes with changing blood sugar and so, the CGM will often tell you a number that is “what your blood sugar was about 20 minutes ago”. even if you are seeing a horizontal arrow, where your CGM is saying your blood sugar is changing at or less then 1 mg/dl per minute… the number can be off from reality by as much as +/- 20 mg/dl due to interstitial fluid lag only. if your arrow is not horizontal, then even more difference between CGM and finger stick is expected.

a word about finger stick. When in doubt, trust the finger stick… however… I cant calculate MARD by finger stick because my finger stick also has a MARD, there is no way to prove the absolute value without a simultaneous clinical blood test, and by today’s standards, the MARD of a typical finger stick and a typical CGM reading are equivalent… I cannot possibly know if my errors are additive, so I have to assume they are, meaning that if your blood sugar by finger stick is 100, then your real (absolute) blood sugar is 80 - 120 mg/dL and so a CGM reading of up to 168 mg/dL considered accurate! (worst case… but accurate). this gets worse and worse the higher the number so when I see my CGM say 230… then I know 1 thing… that I am high… my absolute blood sugar, I dont honestly know.

anyway, and I am sorry for the rant… I work with high accuracy sensors all the time at work and this issue is a “trigger” for me =) my only point is that the CGM, in my opinion, is reasonably accurate, if you know about lag and about interstitial fluid and dehydration and about the accuracy of your finger stick meter… and when to calibrate and (probably more important) when to NOT calibrate. The CGM is a tool, it is a guide, not an absolute number, and your success depends on your ability to use the guidance of your instruments and your intuition and reasoning to make the next best decision. cheers and good luck!

We have a had few issues recently. I’m not sure why that is…bad lot during production or something maybe? I’ve had to get two replacements within the last month. One was a midnight low and sensor failure, where we treated with a juice box only to find the finger stick was over 100. Lost sleep over that one, along with the resulting high alarms from the juice. As a type one mom, it’s hard to not treat first when you see 65 double arrow down! The other was off more than 70 points, about mid 10 days into the sensor. However, I’m not sure I agree with it being an issue with your body, and it’s not like it’s easy to just “find a new system” with insurance companies regulating treatment. One thing I might suggest is Dexcom has a really easy way to contact support and send an issue all online without having to call. I’ve used this before and you just go to the Dexcom website and answer a few questions relating to the issue and submit the information. Then I received a couple of emails saying they received my request and a replacement sensor was being shipped. You might want to give that a try. It could be possible the Dexcom employee was having a bad day, not that I’m justifying the response you received, but they are people working in a call center, and I could see getting poor customer service just as with any other call center. We are anxiously waiting to hear the G7 and Tslim are working together, and hoping for better accuracy!

Not going well. I have had so many issues. I am despond’s t to be honest

Spooky, that’s unfortunate. I’ve been there with my CGM issues before. I hope it resolves. I never thought my Medtronic would turn around……I had written it off……but lately, something happened. I hope it holds.

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Thank you :blush: I was like that four years ago when I started the T slim. I almost gave up and once I got it working, it’s really great.

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A late thought just came to mind - are you staying hydrated? Lack of hydration can affect CGM accuracy. Just thought I would toss that in.

a late reply but yes, I am drinking tons of water. I have had two sensors now that have functioned since this post. I really don’t know what has been happening but am now just so anxious every time I have to switch one out.