I was just told by Dexcom support that sensor failures are usually caused by the user

Did the app say “replace sensor”? If not how did they fail?

I’ve not experienced that many sensor failures but have had a few and in general these failures are obvious in that the glucose jumps around for no apparent reason (no compression, no Acetaminophen, no major unexpected sugar intake or unplanned exercise) and I’ve seen this occur on day two or day nine or any other day.

I submit the failure to Dexcom and they send me a replacement with no complaints. This has helped me to build up a bit of a backup supply.

On the other hand, I have often been able to pop out the transmitters and get a second ten-day use from sensors. So I am ahead in that regard as well.

All of which helps me for the eventuality of losing coverage, or taking a trip where supply would be difficult or multiple failures in a short stretch of time that otherwise would leave me with no Dexcom at all.


How do you manage to pop the transmitter out of the sensor’s bracket without damaging the bracket???

@TJKoko There are some links on how to reuse a sensor elsewhere on this forum and utube video somewhere but I never find it as straightforward as it’s described.

You need to free the little clips on either side of the transmitter and it will pop out.

For me, the hard part is freeing both the clips at the same time and always takes me a few minutes of fiddling. I use a thin but stiff piece of plastic, a medium guitar pick will do it. It’s just a bit closer to the round end of the transmitter, where the sensor has two very small tabs that hold it I place.

It then needs at least 15 minutes of disconnection or it will give the massage “no reuse of sensors allowed” and you’re back to square one.

Remember to “stop sensor” if you are doing this before the sensor expires on its own.

And keep your old code, you’ll need it or you’ll be recalibrating multiple times over the secondaries day period.

@TJKoko I had 3 fail in a row last March. They were wildly inaccurate but wouldn’t take calibrations. But 3 sensors in just a few days. The first I purposely called Dexcom because it wouldn’t keep the calibration, it just kept reverting to a way too low number. Then when the second one acted up I called and asked if it could be the transmitter as I had replaced the transmitter with that first sensor. In both cases I was told, no it’s the sensor. 3rd sensor failed again, that time I changed out the transmitter and sensor and it worked. After nine days I called them and told them changing out the transmitter and sensor worked. I was then told good you changed out the transmitter as we have been having a few people with the same issue and you have to change the transmitter… sigh. It had been a very frustrating few days. They replaced all 3 sensors and the transmitter with no problem.

Here is videos on how you restart and pop out a transmitter. It’s a great way to build a back up supply. Plus the G7’s look like you can’t restart, but if you build a backup of G6’s you can carry that forward to build a back up of G7’s.

If someone had Dexcom is saying that, then they aren’t exactly wrong, but they are very poor at communicating.

The largest single cause of sensor failures is physiological. The user (sentient being) has very little to do with it. The user’s body is the reason.

Your body is a critical part of the system that Dexcom has no control over.

The same thing is true of injection sites and infusion sites. Any foreign entry into the skin triggers a response by the body. A persistent entry causes the body to start aggressively surrounding the foreign object with a sheath of wound bridging material that makes fluid flow to and from the foreign object more difficult.

In short, the body forms scar tissue under the skin within the fatty layer. If the intrusions are short and not repeated frequently then that scar tissue may dissipate. If the foreign object or the area it is within is flexed or moved beneath the volume of scarring is increased.

That’s not to say that Dexcom doesn’t have quality control issues, but MTBF increases with component count and uncontrollable variables like time and environment… The G6 sensor/transmitter/inserter have a lot of mechanical components, exposed electrical contacts and rely on a battery whose working life is shortened by any delay in the manufacturing and supply chain, and the sensor wire can be damaged by excessively hot or cold temperatures.

But having experienced many infusion site failures that were completely resolved by pulling the steel cannula out and reinserting it 1 inch away I believe that Dexcom is correct about failures more being from physiology than from a piece of precision coated wire,

I’ve had to replace eight G6 sensors in 16 months. Each time it was an inconvenience. Each time Dexcom shipped me a free replacement. Each time the replacement, located in a different, noncontiguous site, worked.

I’m waiting to see what the G7 sensors are like. I expect them to be more reliable. I do not expect them to work perfectly.

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To pstud123 Confused on your statement of pulling the sensor out and reinserting it, How are you doing that.
Now on to Sensor Failure. In previous statements from Dexcom they referred to the fact we were the cause because of compressing the sensor too tight against the skin. I call BS on that. I wear a Sciatic Back brace and it has the sensor highly compressed. But I have kept track of the Sensor Failures that I have had and documented them.
In the last 15 Sensors I’ve worn since starting this tracking it has ALWAYS been on day 9 and 10 that I get the failures. Yes they go way and usually happen 3-4 times in the 24 hr period. I change sites every 10 days and have never been able to restart a sensor (early on I tried). In my mind set this has all started when the release of the G7 was first announced. But what I don’t understand is why the people using the G7’s on their arms are having this same issue.
It’s almost like the sensor knows it’s time is ending and is going into a shutdown practice mode.

I didn’t think that “infusion site failures that were completely resolved by pulling the steel cannula out and reinserting it” was in any way unclear.

I was explaining how I identified that sub-dermal scarring was a problem with cannulas. I realized that since both infusion cannula and CGM sensors are foreign bodies, with CGM sensors a longer term intrusion, that they likely share site scarring causing poor interstitial flow to the “intruder” as a likely cause of failure.

Compressing a CGM sensor site restricts interstitial fluid flow. If it were moderate consistent pressure in the absence of scarring in a good site I believe it would manifest as a delay in sensor response rather than a sudden failure.

But if the compression was uneven from bending or movement, it could move the tissue relative to the sensor wire and cause more irritation than average, resulting in faster scar formation than average or lateral movement into existing unabsorbed scar tissue.

In your case, if the uneven compression was consistent over time and moderate in strength it could explain why you experience 10% shorter sensor life than average.

My experience with G6 sensors is that they are not reliably accurate during the first 12 hours and the last 6. I experience compression lows during sleep and occasionally when working under my car. I’ve had 2 sensors that were erratic from the start, a few that didn’t stabilize in 24 hours and some that started acting erratic after 5 -7 days.

BUT I did MDI in my abdomen for +40 years before starting to wear CGM sensors and infusion set there. I expected problems and I rapidly found that there were sites where neither will work.

I had a much larger supply of these infusion sets than CGM sensors. They have limited relocatability. The cannula can be replaced without changing the tubing or cartridge. It was less inconvenient and costly in time to replace a cannula and waste 3 units of insulin than a sensor. So I used infusion sites with steel cannulas as pathfinders for good CGM sites until I mapped out my entire abdomen. Since then I’ve had a few sites degrade for infusion so I’m giving them a rest.

I keep a BGM and glucose tabs at my bedside and during the day I use XDrip+ to give me useful alerts and a display that lets me see whether I have a sudden drop that is unrelated to food and insulin, more likely a compression issue or sensor failure, or a long slow drop. I expect compression alarms when I sleep, and now automatically turn over if I get a beep.

I know this is an older thread, and I never paid much attention to the sensor failure messages as I only over the years had them occasionally. Dexcom’s train of thought has always been that it is caused by compression of the sensor and Tx. I shouted BULL to this long ago sense I wear a back support belt.
But as of late my last three sensors out of the same box have worked well for me for 7 days then all three started with the sensor loss at night. Again there is no compression going on. Don’t wear my back brace to bed. And all three will do it several times a night. What I have noticed is that my glucose will be tracking along between 140- 150. The the next 5 min reading is 80 causing me to react to a low reading . Then no reading for 5-10 minutes before it finally give the sensor failure message.

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This is a common failure sequence for Dexcom. It’s not compression or signal failure but appears to be an issue with the actual sensor lead in the body.

I’m sure Dexcom is aware but not acknowledging the problem because it doesn’t affect the majority of users.

If you get these, please do a finger stick to confirm before hitting the carbs.

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WOO HOO just completed my second sensor session out of five and had NO SENSOR FAILURE ISSUES. interesting part is SUPPOSEDLY these failures are our fault according to Dexcom.
Now when the only change I’ve made in these five sensors is to move the from one side of my stomach to the other. And no change in my sleep patter as they only happened at night. Interesting though the first thee with this issue came out of the same box.