Repeated Dexcom G6 failures


I was told the same, @Thomas, on a recent call to Dexcom. They recommended removing my old sensor and waiting 10 minutes before inserting a new one.

I’m doing a little research for a CGM comparison I’m doing, and I wondered if you guys could tell me what the most common errors are with the G6. I’m very familiar with the Guardian’s errors, and the Libre has very few (one, I think), but I’m still getting to know my Dexcom. I do think waiting that 10 minutes has minimized the amount I’m seeing, but are there common ones that I can expect to run into?


I upgraded from Dexcom G5 (after 14 months) to G6 about 4 months ago. Of the 12 sensors I have used 4 suffered various failures. That is a 33% rate of problems (less than what I experienced with the G5).
First I would comment that Dexcom Tech Support was very agreeable to replace each of the sensors I claimed had failed. Note: it generally took a week to get the replacement in my hands. A serious problem if you have no spares.
The G6 is noticeably more accurate and reliable than the G5 I previously used. But it is not perfect. You still MUST do periodic glucose meter checks to see if it is accurate (I recommend at least 1 per day - I do 3 checks). With the G5 I was frequently seeing a 80-120 unit difference between the G5 and the glucose meter. This is always bad but especially so if the actual reading is much lower than what the G5 reports.
The G6 failures included: 1. Sensor simply stopped working after 3-5 days. 2. G6 sensor consistently 100+ points off glucose meter reading for 2+ days. 3. Sensor package simply fell off (adhesive failure). I was very calm and descriptive in talking to Dexcom Tech Support and they immediately shipped me a replacement.
In case anybody is wondering there will never be a perfect system. I have had glucose meters give highly erroneous readings from time to time (I have a backup meter from a different manufacturer). This is the main reason why I am not a proponent of coupled CGM and insulin pump systems. You are asking for real trouble relying on such a system.
I did research on CGM systems for a commercial pharmaceutical lab back in the mid-1990’s. Progress has been achingly slow but is finally moving ahead.
The G6 is a useful device for self management of diabetes. It is not perfect, but does provide a way to improve glucose control. It also is very useful in alerting the user to abnormal / dangerous / unexpected situations. This can be critical for users who are driving or doing other activities where glucose awareness is vital.


I just joined this forum so I could comment on my G6 experience (love the forum name BTW).

I upgraded from the G4 to G6 about 4 months ago and have also had a sensor failure rate of about 33%. The failure is always the same, 30 mins into the warmup period, I get an alarm and a sensor failed message. I place sensors only on my abdomen and follow Dexcom’s directions carefully. I did stop using Skintac after reading in the G6 IFU that it should not make contact with the needle insertion area. So I started using the Dexcom provided overpatch which is very, very effective at keeping the sensor in place.
For the most part, Dexcom has been super about replacing sensors. However one day I had 3 sensors fail one right after the other (all failures the same as described above) and was almost in tears with the frustration. I had no more sensors at that point and called Dexcom who said they would replace them but they never did. So I had to wait for 3 weeks to get my next insurance approved shipment from my distributor (not Dexcom).
I am also thinking about switching to the G4 or G5 system. Despite the fact that the G4 was more painful to insert, I never had the performance issues that I have with G6.
I am interested in the advice given regarding waiting 10 mins between ending one session and starting another. I will try that in 10 days.


It stands for “For Unlimited Diabetics”…but the other meaning wasn’t lost to us when setting it up. :slight_smile:


Thank you for contributing. You aren’t the first and unfortunately probably not the last to have problems with the G6. They sound very frustrating, and I am really glad that we have had zero problems through our first two shipments.


Hi @Vashon and @funk! I had no idea you guys had responded to the question about the errors. That was a lot of really good information, and I’ll read again in a bit and then respond. I just started on the G6, and so far it’s been pretty solid. I couldn’t agree more though about using a pump that is based on CGM. I’ve just done a year and a half 670G tour, and it blew my mind how messed up my numbers could get as a result of inappropriate actions by my pump… Really this was just a symptom of sensor lag. I’ve just started on the T:slim a week ago and was very worried it would be a lot of the same, but it hasn’t been. For me, it’s a better sensor with a more flexible suspend feature, and it’s looking pretty good.

Said I’d be back and then got to talking. I’ll be back. :grin:


I have Hyperinsulinemic hypoglycemia, and my endocrinologist ordered CGM, the Dexcom G6. I received 3 sensors and a transmitter from my pharmacy. Two sensor were faulty, (example, halfway through breakfast one morning I got an alarm that my BS was 42. It was 125.) The third sensor worked like a dream for four days, then went haywire. Dexcom sent me one replacement sensor, and when I applied it, the wire lodged into a blood vessel and blood filled the transmitter and soaked through two layers of clothes. Dexcom said I would have to have a new transmitter. They sent three replacement sensors, then suggested I have my pharmacy replace the transmitter and bill my insurance. After discussion, they agreed to send me a new transmitter which should arrive today. I have my fingers crossed as I really enjoyed the four days the G6 worked. Thanks for listening!


Listening is what we exist for. I am sorry to hear about the problems. I hope they are just manufacturing issues. We have used 12 or 13 sensors so far, with all but two lasting 10 days, and one of those made it to 9.5 days. The other failure was when it was inserted into a blood vessel and just didn’t work right.


Thanks! The 6th sensor I tried worked! Today is day 10 and I’ve gotten the alert that it will expire soon. After a really poor start, the last 10 days have been a game changer. I only have one sensor left, and I’m nervous about applying it, but hey, a little suspense will hopefully help keep my BG up for a while!


Good news update! I wore a Dexcom G6 sensor for 10 days and it worked well! I applied the last one I have this morning, and it appears to be working!


Glad to hear it. They really are nice and easy to insert aren’t they.