Dexcom G6 sensor performance very erratic?

Most of this post is just me venting on a Sunday afternoon at NFL halftime so take it with a grain of salt, but if you do agree with me, I’d like to hear your opinion.

I’ve been wearing a Dexcom G6 for a couple years now and my gut feel is that their performance has gotten a lot more erratic and inconsistent and unreliable in the past year or so. I often have multiple periods during a single sensor session where it will conk out for a half hour or more, frequently several such times in a single day. A moment ago my Tandem pump honked at me and said my BG is 60 and dropping. My finger stick said 102! This is common for me! And all I was doing was sitting in my recliner watching endless halftime commercials! No exercise, no lying on my side in bed compressing the sensor, just sitting here expecting it to do its job!

Recently one sensor did that nine times in a 13 hour period! I called Dex and of course they replaced it, so they get one point partial credit for that, but that quality control is unacceptable IMO! My life depends on these things!

Anyone else have the feeling that their quality control,isn’t what it ought to be?


Do you have a low BMI? Dexcom is pretty flaky for low BMI individuals, especially those that keep their BG regularly 100 or below. BMI 19 or below.

Low BMI? :laughing::laughing::laughing: I should be so lucky! I wish! I would quibble with anyone who called me obese but I’m definitely pear-shaped. And my BG bounces around like a ping pong ball in a tornado! I regularly top 200 after a meal and stay there hours longer than the textbooks say I should for a proper amount of insulin. I count carbs very well, and I regularly dose for carbs plus BG as I’m supposed to. But even with that, I NEVER go 24 hours without dropping below my self-defined monitoring limit of 85.

As an example of my sensor issue, it just conked out again an hour ago, at BG just above 180, after showing that my BG is dropping sharply. No readings at all since then for nearly an hour. My finger stick said 220. That’s what has me so aggravated. No sensor, no credibility on what it last said, etc.

And this is what I’m trusting to send reliable data to my pump so I get the right insulin dosage! :rage::rage::rage:

@Tom_in_SC I am having similar experiences with the G6 sensors, but I have only been using it for 9 months. The last sensor was the worst with false lows and dropping out for 30 minutes to near 3 hours multiple times in a 24 hour period. The ones at night are extremely frustrating as the alarms from the false low are then followed sometime later by the loss of signal.

Getting a good nights sleep is essential to good BG maintenance, so this is counterproductive.

These sensor problems generally begin around day 7, but have happened as early as day 5. The loss of signal is almost always preceded by a sudden BG drop over 15 minutes (3 or 4 dots). Those false lows aren’t due to compression as I place the sensors on the abdomen and I never sleep on my belly, plus the happen, as well, when I am awake, walking, sitting or driving the car.

Dexcom has replaced several of these sensors, which is nice, but I would really like to know if there is a problem with the quality control on sensor manufacturing.

It is good to see your question, which confirms my experiences. Most on the diabetes forums seem to praise the G6, and I am with them. For 7 days it’s wonderful, afterwards often not so great.

One thing, may be pandemic related. There could have been disruptions in supplies, personnel and other things to make the current crop of sensors not up to usual. This might include problems with adhesives (allergic reactions), sticking applicators and our problem with sensors, Tom.

It drives me nuts, because I spent much of my life monitoring, diagnosing and repairing complex electronic systems. My first rule is after, Is there power?” Is to look at cockpit error, “is it being used correctly?” Then comes looking for actual trouble in the system.

To try and understand CGMs I have read scientific papers, taken used applicators, sensors and even transmitters a part, but without proper testing equipment this is mostly a fruitless endeavor.

Sorry for the long post, when I am frustrated I get wordy, according to my wife and children, then I must always be frustrated, :crazy_face:

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I find that when my sensor acts like that, it has a problem, almost always from improper installation. Sometimes the wire doesn’t go in all the way. Or bends a tiny bit
It will be fine a few days then it goes nuts.

I have been using the G6 almost since they came out. I like you was super worried about it not being accurate (was using G4 before & never dosed off the sensor) and letting my pump dose from it. But one of the doctors I work with doing clinical trials said to just try and let it do it’s thing. I did. I stopped testing and haven’t looked back. Keeping my fingers crossed it continues that way for me.

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Timothy, how do you install your G6 sensor? Are you the person who suggested lifting the device a bit instead of pressing on it when inserting the sensor. I have much less of a problem with sensors when I lift them. Sometimes though, the sensor still does not work for me.

Sally, if I did what you do, I would most likely be dead. Would you please tell me how you insert your sensor? Sometimes my sensor readings and my finger stick readings are widely off. I don’t use a pump.


Nothing different than what the company says. But I do use other spots not just the abdomen. And I must be very honest here, I was so afraid of trusting the sensor & pump to do it’s thing. I am pretty sensitive to insulin. My correction factor is 1:100 most of the day. I was super wigged out about it being off. I mean when I make a basal adjustment, I can go from .35 to .3 and it takes care of the problem. But I let go of my having to control everything and let the system ride. And for the most part, it works perfectly for me. Sure sometimes I have to help with another mini bolus to take care of a high as it’s not as aggressive as it could be, but it is very sweet to not have to worry about it.
I am very fortunate that I usually do what most people do and it works. Not a lot of tweaking.
I wish I had an answer for you but the G6 is the first sensor I have used that I don’t double check it.

Thanks Sally7. I think that it is great that the G6 works so well for you!

I have always had unreliable results on the first day of a new sensor. It happened with G4, G5, and now G6. After that my sensors work great. At the same time I rarely use my meter after the first day. But I don’t find the sensor giving me crazy, unexpected numbers.

You are not alone in thinking there has been a reduction in quality of sensors lately. Lots of people on Facebook say the same thing. That is not my experience but it doesn’t mean that your experience isn’t valid.

I once heard an interview with either Kevin Sayer or another Dexcom executive who said that certain people have reactions to the sensor wire and that explains the errors at Day 7-8. I have an online friend who experiences at least 75% of her sensors failing at Day 8. I have never had a sensor fail at Day 8. Or maybe once?

I am more comfortable with inexactitude more than many of you. Here is a blogpost I wrote in 2013 when I was already dosing insulin off of the Dexcom G4. It hasn’t killed me yet!


Have you tried presoaking? i.e. inserting new sensor 12-24 hours before the current one is done? Works wonders for me. No more zany crazy readings in first 12 hours on a new sensor.

Yes, I have tried presoaking. Amazingly it doesn’t make much of a difference. I have found that if my BG is above 120, I get a better sensor start. If I am below that get LOW! and readings that are much lower than my actual BG. I have given up fighting the battle and just turn off Control IQ until I have reasonable sensor readings.

I am fortunate in that my readings, no matter what BG is at insertion time, are 95% reliable. If i see a BG that seems wildly divergent from how i “feel” (too high or too low), then i check with a finger stick. If off by 20 to 40 or more points, 90% of the time a recalibration does not help and the sensors start reporting errors. Sensors also tend to get errors after 7 to 8 days. Even with insurance, the sensors are costly, so i cannot let that pass. Contact Dexcom for a replacement, no additional cost. Unless they face the cost to replace most sensors that fail, they will be disinclined to do the research that will make them reliable. At least 50% of my sensors fail after 7 or 8 days. Here’s a link: Product Support Request.

[Note: i always power down the receiver and recharge it, insert the new sensor and let it soak for about an hour, then power the receiver and begin the session. I also use Skin Tac from Amazon (bottles last longer than wipes and are better value, but perhaps not always convenient) and the free Dexcom overpatches to keep the things on. Otherwise, they fall off after 4 or 5 days. Yeah, quality control issues. But, waaaaay better than finger-sticks a bazillion times a day. At least for me.

I to have noted frequent drop outs but in my case it’s always othe last day of sensor life and even more frequently near the end of the Tx battery life.
But all in all better then the G4 and G5 series

I have the exact same problems. The dexcom is often off many crucial points. My doc said to just watch the arrow key instead of the numbers. But why am I wearing this thing then? Also my pharmacy asked me why I needed test strips if I wore the dexcom. I told them no way would I give up my strips!! And I still test frequently. I’ve seen the commercials stating no more finger pricks and I say bullcrap!!


I like other users here often get a bit wording when frustrated so I’ll endeavor to make this short! Yes! We have been using the G6 pretty must from when they were first made available and I believe there is a pattern that shows less reliability and accuracy more recently than in the beginning. Wonder if there has been a change in manufacturing, but those kinds of questions won’t most likely be answered. Having said that there are so many variables as to why this might happen. I for one always check the sensor wire to see if it is bent in any way or broken. Our experience has been similar to Tom_In_SC’s.

It is troubling to hear that others are having similar experiences. We totally rely on our Pump/CGM working “most” of the time and being fairly accurate during that time.

I remember those commercials - interestingly enough they are gone now from our area anyway! I think the commercials are gone specifically because of those statements…

Yes I stick the sensor tape. Then I lift up before hitting the button. It opens more space and the wire is less likely to bend.

Hey Tom, I thought I was the only one experiencing these issues with my Dexcom G6 but I see I am not alone which is unfortunate, but good. Maybe if enough of us complain something will get done. My Tandem gets 3 dashes and reports no reading, it prompts me to change my sensor before its expiration period and it seems the transmitter battery in the G6 doesn’t last the full 3 months. Dexcom is failing to meet the quality control requirements as well. SHAME on them!