Dexcom G6 and G7 not lasting full 10 days?

​For over a year now I’ve had problems with both G6 and G7 not lasting the full 10 days. Typically I get weird numbers or they just give the 3 hour error and never come back starting around day 7 or 8.

I’m not sure, but I’m beginning to think it may be related to how much liquid intake I get.

Anyone else have similar problems and if so, what did you do?

I have used the G6 for 3 years and experienced the 7 day failures. I only reported about every 3 failures because I only have so much room for D stuff. This allowed a small build up of sensors.

These 7 day failures is a not universal, but is fairly common for some of us. It may be something to do with our unique biochemistry or immune system attacking the sensor.

Those that don’t experience this phenomenon will think it is compression lows or something else. In the image below, it might appear to be compression lows, but this happens while walking around and never for me before day 7.


Mine are due to a combination of bad sensors, especially during the last 15 days or so of transmitter life. A bad sensor which is usually part of a batch of bad sensors shows skips like you show in your graph. Those same sensors, however, toward the end of transmitter life skip, show crazy results all over the place and then a sensor failed replace sensor message appears in day 7, 8 9 or 10.

Right now I am running parallel Day 1 on both a G6 and a G7 and there is between 40-70 points difference between the two and finger stick BG’s fall somewhere between the two, but mostly closer to the G7


When doing a sensor change are y’all cleaning the gold contacts on the transmitter with an alcohol wipe?

Nope, on the G6 I just wipe the gold contacts with my shirt, handkerchief, or whatever else is around when it is time to change the transmitter to a new sensor. I have never used an alcohol wipe for MDI injections, sensors, or anything else diabetes related.

While I am one of those where the G6 sensors nearly always last 10 days, and if restarted, last another 10 days, I have become convinved it really varies by the person’s body. Of course, for some, it could be a bad sensor, for others it could be a badly-installed sensor, but from reading all these posts, I’m convinced most sensors that don’t last 10 days are due to the particular body.

You would think Dexcom has researched this, but as far as I know, they have not published any findings. I guess their business model is simply to send out a replacement sensor if one is reported to fail prematurely.

Yep, but as @CJ114 does would most likely work as well. I just often see an oily residue on the transmitter that I like to clean off.


Luis describes this well – his graphs could have been copies of mine. I agree that it’s very much a biological difference among patients. For me, sensors (G6 and G7) are seldom reliable beyond 7 or 8 days. After about 6 months on the G7, I’d say it is slightly worse than the G6 in this respect. (If it weren’t for the software improvements, especially the ability to avoid a gap between sessions, I would have preferred to stay on the G6. I’m not persuaded that the actual G7 sensor wire is anything but a shorter version of the G6.)

For me, I see no batch (lot#) correlation. Of course, it’s hard to make a correlation when nearly every sensor fails. (“Nearly every” is perhaps a bit unfair. It’s actually about half that fail me early, both G6 and G7.)

I try to report every failure, because I want the failures entered in Dexcom’s records. I’ve tried telling them not to send a replacement, but they don’t listen. I’ve given away extras via

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If I remember correctly the G7 sensor lead is shorter than the G6. If an immune system attack on the reagents or a chemical difference in some individuals is reacting with the reagent, shorter lead probably will fail more often.

If our docs were allowed they could prescribe 12 sensors for 90 days

Luis’s graph really looks like a bad connection. Cleaning the transmitter and making sure to snap the transmitter into both clips in the sensor are about all we users can do about that.

Sweat combined with lotions or oils is a possibility. It could also be the sensor is loosing contact with the interstitial fluid.

I’ve had a few sensors go wacky before 10 days. The times the problem wasn’t obvious like blood or loose adhesive not holding the sensor in place it because I had tried a location further away from a known good area.

I actually removed the transmitter, which had clean connections, and restarted the sensor. I did this twice, got the same results as before.

I used a little microscope gizmo to exam an unused sensor contacts and lead and failed sensors and those that lasted 10 days. The conclusion was indeterminate. It would take a real laboratory to maybe find the problem.

This is a known problem for some. People who always get 10 days and those who restart successfully always think it is user error, contamination, or transmitter issues.

I am retired but am trained in troubleshooting electronic and mechanical devices. Dexcom just doesn’t want to be bothered to do the work to give a correct answer. The people answering the phone are not those who can answer.

My graphs look very similar – using G7. Nothing to clean or clip.

I’ve seen plenty of Signal Loss. Those look very different from what Luis and I are presenting.

I accept that even though CGM is a huge step forward, it simply doesn’t work as well on my body as it does for some. But I hope that by posting, I help to clarify the situation to others who react similarly, and to tell people to stop claiming it’s something we might be able to change.

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Not to hijack this thread or anything, but I called my insurance who uses CAREMARK and explained what’s going on. I asked them if my MD wrote for 4 boxes of 3 for a total of 12 G7s per 90 days would they cover it? He did a test claim and it came back ok. I guess that is an option for future? When I asked my endo at last visit, he said most insurance companies won’t cover more than 9 for 90 day supply and to just keep hounding Dexcom for replacements whenever they fail early.

I typically use the online request form, but I know that after a certain point supervisors needs to approve replacements and it’s ha hassle. Would be easier to just have the script re-written.


Almost all of my G6 sensors make ithrough 10 days, no problem at all.

The occasional sensors - less than 5% of them - that do crazy dives followed by (within an hour) corrections, tend to do them after day 7 on the sensor and after 80+days on the transmitter.

My pet theory is that it is related to transmitter battery being “low” or related to grime film on the transmitter contacts. I do alcohol wipes on the transmitter gold contacts almost (but not quite) every change.


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I’ve only seen this kind of breaking up pattern at the end of use once in 18 months, then sensor readings dropped off the bottom of the scale and triggered an error.
I learned early that taking a shower or heavy sweat could short the transmitter contacts and found out that removing the transmitter ans cleaning the contacts of sensor and transmitter could restore it to operation. I’ve had more than a few sensors that were unusable for the first day or two, and got accustomed to using a BGM for the first 24 hours and calibrating the G6 with it. I’ve had sites that would experience compression if I sat wrong or used a laptop.

It would be interesting to have biometrics like BMI and age of diagnosis, and where the sensors are worn from those who have frequent issues and those who never do. It’s definitely a case of one size not fitting all.

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No. I didn’t see directions (in the Dexcom sponsored youtube videos I watched) to do that. (By transmitter, do you mean the sensor?)

I am a new Dexcom G7 user, currently wearing my second sensor. The first sensor lasted 10 days. I calibrated the first sensor very shortly after putting it on, and probably I shouldn’t have, as the readings it gave me nearly the entire 10 days were anywhere from 15-20 points higher than a fingerstick. I have not calibrated the current sensor - the readings initially were too low, I knew, but I suspected that the sensor would “get to know me” and over time reflect the actual fingerstick, and generally it has. If anything readings are a bit lower this time than the FS, but not as wildly different. If I move over 20 feet away from my cel, it will not be able to give me a reading, and gives me a message telling me that.

I thought cleaning the transmitter was in the user guide. I looked at the current version (touchscreen receiver? that’s new) and I dug the manual I had in my bathroom drawer from when I started with dex. It isn’t there. I must have made a mess, probably bled all over a transmitter, and have been wiping the transmitter on every sensor change ever since.
The transmitter is the gray slug that snaps into the clear plastic sensor. I don’t ever touch the sensor contacts, they look that that stuff on the end of a mylar ribbon cable good for two cycles made from unicorns.

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On the G6 lifetime issues. I’ve been cleaning the transmitter contacts for years when the sensor becomes unstable. This usually happens after 8 or 9 days.

I seem to think that if I’m having a period of highs, the time before the sensor becomes unstable shortens to 7 or 8 days. If I have few highs and some low spells, the sensor seems to last the full 10 days.

As to cleaning contacts, only the transmitter can be really cleaned as the sensor has the conductive pads covered in a protective dielectric grease. I’ve used a soft pencil eraser to clean/polish the transmitter’s contacts several times with no change in the failure of a sensor.

I conclude that my sensor failures with the G6 were related to the chemistry of the sensor wire rather than contacts between the sensor and transmitter.

As I’m now using the G7 system, contacts are no longer an issue. I’ve had one out of three exhibit erratic readings on day 9.