Dexcom trace from midnight to 6AM day 9

I don’t know why this happens usually begins on day 7 or 8 getting steadily worse. It is always the same thing, a reading that is correct suddenly drops over 15 minutes to low or urgent low causing an alarm. When it happens at night, I get woke. Last night I turned off my phone, but the pump took up the slack waking me up. These lows have never been true.

BTW these are not compression lows and this has happened during the day when I was up and about. This happened with both MDI and Tandem C-IQ so it is not an issue with basal from the pump.

I know that this is not an uncommon problem as some other experience the same thing, but than, others have good stable readings throughout 9 days with maybe day one a little iffy. And restarters sometimes get up to 30 days of good results.

I am retired, but still a troubleshooter at heart. I just want to know what is the issue at day 7 with these sensors. :rage:

Rant over, Thanks for reading


Ive been experiencing this with my current sensor, day 7. I had several lows last night, 8% false low overall! I think it is just a bad sensor but hate to change it 3 days early! Ive tried calibrating in the past with these bad sensors but it just seemed to make it worse :sweat_smile:


But if its not working, call dexcom support or use online form to get replacement. Extra effort, but get new sensor and more days.


It is so common about 80% of my sensors do this. I did get better results when I began using arms over abdomen, but that seems to no longer be the case. Really what I want is answers as to the technical reasons why this happens to some users and not others.

I suspect the longer use G7 will be worse or the same for people like me.


Yes, same for me, I can only use arms. 80% occurrence is horrendous though. The last few sensors had this issue, but usually it is just occasionally. I put it down to just “noise”. It happened all the time prior to G6 though. I hope this means G7 is another step in the right direction!


Most G6 sensor locations always error on the low side. This is very true towards the end of a 10 day period. My last 2 sensors were very bad. I found out the problem was the transmitter. I did get a low battery warning, but the warning stated it had about 20 days left. With the last sensor change, I also changed the transmitter. All errors are now nonexistent. For the sensor location, arm triceps, my sensors are usually very reliable. The worst ones get bad after about 8.5 days.


I view that as a safety feature. Eating glucose to raise your BG by 60 mg/dL is less dangerous than taking insulin to lower your BG by 60 mg/dL if the sensor is way wrong. There’s just a lot more safety margin going high.

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I know that the sensor is in error when there is a change of more than 10 mg/dl in 5 minutes. Since I always keep my A1C below 6, I know that it is very important not to over compensate either way. I don’t much bolus or basal insulin so I pretty much know what my BG level should be. I also always check the calibration of a suspect sensor. I always track my insulin sensitivity based on my activity and adjust. I’ve been doing this for the last 48 years as a T1D so it is a pretty natural thing. Right now I just glanced at my watch to see my BG is 97 mg/dL with a gradient change of 0 mg/dL. I also have a phone that gets the data from the watch, when the pone is in range of the watch. I have a second identical phone that also monitors Bluetooth port 1 of the Dexcom G6 transmitter. It is a neat thing to hear the data reports from each phone. Port 1 always reports first then followed by port 2. The G6 Port 1 is the port normally used by the Dexcom receiver.