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

My feelings about Dexcom are starting to change. I’ve been using it for about 6 years now, maybe longer, and the past 6-12 months it’s been more than obvious to me the quality has nose dived. Used to be sensor failures and/or wonky readings were rare, very rare, now lately it’s like 20% of them either read incorrectly or don’t last 10 days. Used to always get 20-30 days out of a sensor, now I’m lucky to get 10 days.

So just had another one fail after 6 days so I called support. Of course they replace it, but I mentioned what’s going on with the quality of these sensors lately. His response? ‘Our sensors go through extensive testing before they are sent out, we rarely get reports of bad sensors. Usually it can be traced to user error’.

Yea, ok.

Done venting.


EVERYONE is complaining about the change in quality. The techs have no way of knowing how any one person’s experience has changed, let alone the collective group of us. They handle the same number of complaints every day as they used to, because that’s how the que works, from seemingly different people.

Have you by change been looking at the manufacturing dates on the crappy sensors? Mine all seem to be from the height of covid, when there were supply line issues. Well, I guess there still are, but they’ve definitely gotten better. I’m wondering if the reduced quality is due to a change in manufacturing, such as different raw material supplier(s) or using less reagent.

They also opened a new manufacturing facility in Malaysia around that time, so maybe that’s relevant?

The uptick in replacement sensors has to be costing them money, so I hope they’ll revert back to the old quality.


In my opinion the people who answer the phone do not really know what is causing the issues we are having. Perhaps we should start reporting these failures to the FDA or whatever in other countries.


All valid points. I truly believe I received a bad batch that covered a 3 month supply that appears to have been manufactured in April of this year, so not sure if Covid played a role or not. But I know every sensor that they sent me as a replacement worked perfect, while more than half of this batch did not. What got me though was this tech telling me that USERS reporting sensor failures is rare, I don’t buy that for a second. I’ve been seriously thinking of trying the Libre 3 but so far it doesn’t appear that it’s yet compatible with looping with AAPS.


There are quite a few of us. I have been using the G6 system for 2 years. I have had quite a few failures over the 2 years. Some have been false lows, not compression mind you, that caused be to over treat. That has taught me to do a finger stick to check.

My usual problems start around day 7 with a loss of signal, usually accompanied by a sudden drop in BG numbers over 15 minutes to a low or urgent low (not real). Then a 20 to 40 minute wait for data to resume.

If this was user error, why does it begin on day 7 or 8? And I am not alone in this. Someone on Reddit suggested that the sensor lead on the G6 is a different length and angle to the G4 and 5. I have no idea, since I have only used the G6.


Can confirm! I’ve had major issues with g6 sensors especially in the last few months. Mine usually go unreported and I just pop in a new one. The quality has dropped and they sometimes just stop sending data for 2 hours then randomly start up again. But often it just says sensor error and refuse to start up again.

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No libres work. We are stuck with Dexcom, but I appreciate your raising the issue of quality. They are not what they used to be. I spoke with the Doc about this and had the same thoughts. She told me to, “man up.” She was right. There’s no viable alternative. The first place this issue is documented in writing (that I know of) is here. It started when covid started. Open Source Medical Device Safety: Loop Artificial Pancreas Case Report | IEEE Conference Publication | IEEE Xplore

The suspicion, at the time, was manufacturing failures because it coincided with the onset of covid and because we started seeing entire lots of sensors fail. But, we never made any progress in uncovering what changes in manufacturing occurred or attributing failure to any specific source.

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Not me. On day 20 of current sensor. Usually get 15+ days if I restart.
Have only had 2 replacements in several years.


It’s been my experience that when/if you get a bad ‘lot,’ you’ll know because the whole box will fail the 20/20 test, sometimes by a bunch…maybe 50 - 75%. I think it’s still relatively rare, but across a large number of users, you see it pop up. I never saw this happen in 10 years on G4. But, its tricky because we had a collision of many factors - upgrades from G4 → G6, covid and resulting manufacturing pressures, etc.

Word on the street, here in town, is that viable alternatives to Dexcom have been engineered and had great accuracy. A Japanese company built one. But they were bought out before getting to market.

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I track lot numbers and have yet to see a correlation between failures and lot numbers.


By ‘Lot’, I mean box, or box of boxes from my distributor. Good catch. Could be freezing during transport or something. Every replacement they sent me worked fine. Any sensors out of that shipment - bad.

We should freeze some sensors and see how they behave.

People in town are still seeing supply chain backups from when TX froze last year and damaged a bunch of stuff sitting outside or in warehouses. Texas Winter Deep Freeze Broke Refining, Petrochemical Supply Chains - Dallasfed.org

Who knows! Maybe they rerouted Trane thermoking’s temperature regulated trucks from transport of commercial goods to storage of corpses or more valuable equipment in TX. There’s been unusual pressures on transportation trucks and warehousing.

I suppose covid broke everything everywhere. Why should BG sensors be the exception?

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While I still get half of them going to around 26 days, the other half seem to fail at around 12-16 days. It used to be half failed at 26 days and the other half always went over 30 days. I rarely got less than 26 days before. So something has changed. Although the one I am wearing is 29 days and still going strong.

I get my Dexcom from local Costco pharmacy for past 2 years. Prior to that, did have shipments from DME provider, with a few that needed replacement. Wondered if switching to local pickup led to less failures.

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Don’t stop VENTING. a lot of us are doing it on the same subject. Fexcom “sensor failure”. There is a major difference between Signal Loss and sensor failure.
The first is a Bluetooth issue. To far Far from the Tx. Or signal block by some source.
Sensor failure is just that, the sensor can no longer detect glucose .
Everyone issue is the same it’s started occurring recently.
In five years I’ve never had one. But this past shipment of 90 day. 3 Different lots. 1st one the 3rd sensor failed after nine days. On a different lot the 2nd sensor of the lot started the on and off sensor failure then failed completely 5 days in.
I did not correlate all the failures noted in various post as coming from the pandemic.
In my mind set I started to note these failures in other post with the advent of the G7 being released in Europe.
Which brings up the issue as to why the G7 could not past the muster in the U.S.


It’s a problem and an irritant for sure.

At $100.00 per sensor (that’s what I pay — out of pocket— in Canada) they must be doing okay. But it’s really about growth in the market (and maybe market share).

The manufacturing costs can’t be very high, maybe a few bucks per sensor, to make. The quality of build is pretty flimsy, it seems to me, which is understandable: these are one-time use, disposable cheap junk.

So where’s the biggest cost? I think that they’ve paid it already: development. Now they just want the income stream. They want to keep us relatively happy and the way to accomplish that is replace any failures relatively painlessly.

They do manage that. Five minutes on their website, basically no questions asked, and another sensor is on its way.

I just had one that started giving erratic readings on day five, the replacement will be here by the end of the week.

Even with shipping and packaging costs, I’m sure their marginal cost per sensor isn’t more than $15.00.

Of course the G7 should be even better, cheaper to make, and more profitable. But Dexcom is doing okay financially and it wouldn’t make financial sense for them to pay a lot more $$ for a slightly better product.

Heck, I’ve invested in Dexcom. I see how much CGM has improved my life with diabetes.

Their market cap is $45 Billion. Price to earnings is quite high (about $250) but they’re growing and expecting to chop P/E in half in the next 12 months. That doesn’t mean that they’ll continue to grow at that pace (I can’t picture Dexcom as a $100 Billion company a year from now or share price doubling, or a lot of buybacks, although that could happen) but investors finding something worthwhile is how capitalism works, ideally!


@MBW The self funded costs in the UK for a month supply of G6 sensors and a transmitter is $185. The new Dexcom One which is supposed to be the same sensors and transmitter, but without extra aps like share is $100 a month. Since the sensors are the same and the programming has already been developed for the aps… the $100 per month , is virtually the costs that a G6 could be and they still make a profit on it.

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I’m actually paying $299 / month for sensors AND one transmitter every 3 months is included

I posted about this recently – in my experience, G6 sensors when properly calibrated after installation or restart, are consistently accurate for 20 days – when installed on me.

Given my own experiences with Dexcom G6, including in the last two years during supply-chain problems, I doubt Dexcom is shipping lower-quality sensors. Either that, or they are shipping the good ones to me, but others are getting the bad ones. I kind of doubt that.

Still, I have read many posts here from smart people who are not getting that consistent accuracy, and while I understand why Dexcom Support may believe when there are accuracy problems, they are caused by the user, I am concluding it is more likely Dexcom sensors are not able to be accurate for 10 or more days on some bodies.

I would hope Dexcom has a research team looking at this. I have concluded it is a real issue, and ideally they will discover why accuracy falls off or never is accurate for some people/bodies. Hopefully they will find a solution.

I only ask that people experiencing this problem not conclude that since Dexcom sensors are not consistently accurate on them, the same must be true for all users. In my case, it is not – they actually are consisently accurate.

The only possible suggestion, which is pretty lame, but I offer it up, is if you have had accuracy problems, try the following:

  1. After installing a new sensor, calibrate with a meter several times. Only calibrate when your BG is stable, not rising or falling. When you get two or three sensor readings that are within about 5% (some suggest 10%) of your meter, you are probably done calibrating. Of course, as the Dexcom manual says, any time the reading does not match how you are feeling, then calibrate again.

  2. In case the adhesive on the Dexcom sensor is not sticking to your skin very well, use a 3rd party patch made for the G6 sensor to ensure the sensor stays in place. In my case, the adhesive can handle the 1st ten days, but if I restart, I really need a patch to keep the sensor in place for the 2nd twenty days.

But the above for some people may not help and you are stuck with frustration. I hope Dexcom takes your issue seriously and is already researching the problem. It is not acceptable to sell a product with problems for some users and then just blame the users.


I don’t have any issues with the adhesive. In fact it is a struggle to remove an old sensor, and no reaction to the glue. I generally do several calibrations after warmup because the generally start out way high. Some report the opposite, starting low. Loss of signal to pump or phone is not a real issue. With the pump it is usually corrected by moving the cat :cat2: off of it. With the phone its because its on the table and I am outside. Within 5 minutes, all is happy.

My problem is what starts about 7 days. BG will be steady and then suddenly drop over about 15 minutes to low or urgent low (these are false). Then there is a loss of data with a message to not replace the sensor, wait 3 hours. Usually data is restored in 20 to 30 minutes. This usually gets worse on day 8 and 9.

This problem is not just with me. When you call Dexcom that ask all the same usual questions, Where is it located, are you taking Tylenol, when was the transmitter started? I find that I get better results with the sensor on my triceps or inner upper arm. The abdomen is very bad. This screenshot shows a sensor failure that was replaced.

I will say that my last sensor only did one hiccup in 10 days. I restarted it as an experiment. It was good for 4 days, but day 5 became unreliable, doing lists of calibrations, finally doing the usual sudden drop to no data, so I changed it out. I’ve done one restart of a sensor that was acting like the screenshot. It was horrible from the get go, and had to be changed.

I agree, that it is an issue with some peoples bodies, but this should be addressed by Dexcom. For those who have a history of sensors only lasting 7 days should get 4 sensor per month, not 3.