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. 
Welcome!
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. 
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.
Even using the Skin-tac and Amazon site covers, I’ve still been consistently only getting 7-8 days on every sensor. Support is awesome in replacing them, which makes me think they are aware. I notice that on weeks where i work out more, these tend to degrade faster, even with the thing still essentially perfectly super-glued to me after 10 days.
So my update is that since we’ve switched to using exclusively Samson’s belly AND started using the Dexcom-provided overpatches, we’ve had more sensors last 10 days than not. We have still had a few sensors fail before 10 days but most were sort of peeling a bit at the edges because we ran out of overpatches.
I’ve also noticed that Samson’s sites have been pulling out well before 48 or 72 hours and I wonder if the fact that he’s growing up and perhaps thinning out from his little chubby baby body is perhaps part of the problem in both cases…
Anyways, the G6 is definitely more sensitive to being uncertain about the interstitial milieu, but we’ve found a way to work around that for now!
Just curious, if the original lasted 7 days, then replacement lasts 3 days, then fails, do you get another replacement, or does dexcom keep track that in total you got 10 days ?
In that scenario, in my experience, I believe you can technically get a replacement…
I look at it like my insurance company is paying for 90 days of cgm, so I request replacements to get me to 90 days only. I have infrequently made requests within just a few days of each other. They’ve always been shipped. No questions asked. I guess maybe if they felt like you were abusing it, they might reach out to confirm that you are satisfied with their system and it’s working correctly, YMMV
My experience with the G5 is that, any time a sensor lasts less than its guaranteed duration, Dexcom will replace, replacement sensor or not.
We typically ask for a replacement every time a G5 sensor lasts less than 5 days and don’t bother with the others, it ends up averaging out.
They absolutely replace any sensor that does not last 10 days and they don’t keep track of whether that sensor was a replacement for another one, etc.
We ask for a replacement for every sensor that doesn’t last the full 10 days. We used to be more lax because so many sensors lasted 14, 20 or 30 days so we never had a shortage. But after the summer, where we had so many failures in a row after switching to G6, I’ve become absolutely meticulous about requesting every single sensor that fails be replaced. I have had it happen that, for instance, a sensor fails at 6 days, then the next at 2, 1, immediately. So in our experience you can get into a bad patch that will rapidly deplete your seemingly copious stash of sensors.
I’ve had to have 8 replacement sensors in the first month I had the CGM. I know that Dexcom G6 sensors are on back order. Medicare started covering CGMs on January 1, and a rep told me that they are getting another facility up to speed so they will have more in production. They do have a protocol set up to handle defective product.
@stearner - interesting on the working out and degradation/failure link. I am going to play around with workout frequency and see if I notice a link, too. I think I’ve solved the adhesive issue also (the Dexcom overpatch works well), but I consistently start to get sensor errors at day six and onward. The system typically will pick back up within the three hour window, but I’ll have a few system errors each day, starting with day 6 or 7. It’s really frustrating. I only go to Dexcom for a replacement if I get the error beyond three hours, but cumulatively it’s an issue and it’s not working well for me. (This is D6.) Ugh. Jessica
Yep. Pretty much exactly same experience here. I’ve been sick this week and haven’t made it to the gym and my current sensor is starting to cut out on day 6 so the correlation with exercise may not have been a causative factor after all.
I run OpenAPS, so once the sensor starts cutting out for more than an hour and a half or so, I typically change it because it will almost certainly crap out while I’m sleeping and with Dexcoms replacement policy, it’s just not worth it to me to have it work only intermittently (if at all) for the next 3 to 4 days. When I call Dexcom, I’ll let them know that it might not be 3 hours on error, but the intermittent errors are interfering enough for the sensor to no longer be beneficial for my treatment. I’ve sorta just accepted now that everyones different and it makes me 100% happier not stressing about why my body for some reason doesn’t let sensors last 10 days. Maybe our immune systems are just better than everyone else’s 
It does seem like you don’t hear quite as many folks anecdotally claiming to be getting 20 days out of a sensor any more, so there’s some folks that think they’re intentionally making the filaments finer to prevent reuse now, but I don’t see how they could do something like that without going back through FDA trials, so who knows.
It does make me eager to learn more about Eversense CGM though…it’d be nice to not have to worry about sensors dying slow deaths anymore.
I am like you, I see this as another conspiracy theory.
I have always found Dexcom a great company, and they put out a product that has made an extraordinary change to our life. It makes me angry to see people actually accusing them without a shred of proof.