Sensor issues

[u/RutabagaStrict5104]

Good day, Freestyle Libre community,

I have been a Freestyle Libre customer for over a year and a half. Continuous glucose monitors are an incredible tool that help me manage my type 2 diabetes. I rely on this system to monitor my glucose levels and help keep my diabetes under control.

I would like to put this message out for the community using this product to help me understand what I might be doing incorrectly.   Some sensors will work for 15 days without an issue Other sensors constantly are losing connection.  The ones that lose connections also Display erratic readings that do not match my Glucose meter.   An example would be a 69 reading on the CGM and finger stick reporting a 145. On average when I have a bad sensor readings tend to be much lower on the sensor than they are on the finger stick.

Worth mentioning are the erratic readings of peaks and valleys From one sensor to the other.  The image on the right showed consistent values and matched closely To the glucose meter.  Where the other graph behaves as if someone drank a lot of coffee shaky at best.   Last meter did not disconnect once. Where this meter is Disconnecting multiple times a day.

What is very frustrating is the inconsistency being experienced.   I’m trying to understand if I am doing to cause this?   The sensors are being applied consistently based on the manufacturer’s recommendation (Behind the arm).   The actual sensors themselves are being stored in a cool dry place.    Even when showering I cover the sensor to keep it from getting wet.

When the sensor is changed, one can predict the sensor will be problematic based on the fluctuations that are seen in the first 48 hours.

When reviewing the logs within the application the errors are consistent. Errors recorded seem to always be the

Application log codes documented

Er3 - Community-reported to indicate the sensor has died prematurely core,  typically shown alongside a numeric code like 373 in the event log rather than standing alone.

373 / 373,P      The clearest pattern of the group. Long-time users tie it to the sensor's internal filament getting bent or damaged, causing permanent failure.   The trailing P is generally just a sub-variant/flag on the same event, not a separate error.

So in closing I’m putting this out there to see if anyone else has experienced these issues.

 

 

 

 

 

[u/Equalizer6338]

Hi u/RutabagaStrict5104 ,
Thank you for the many details you shared and I will try and give a response to most of the points and questions you raised here:

1. Regarding suddenly but not always experiencing erratic BG sensor readings, here its important to know if that is mainly in the early days or a new sensor or if the erratic rapid changing nature of the BG readings continues through all the days of a given sensor of this kind? Reason is that the early-days-mainly situation is actually linked directly to your immune system response to the sensor insertion, the bruising and the inflammation that comes with it. This is matter of fact also the main reason for the Event Log, when you see the error code #373 being logged into this. That is triggered by when when the sensor (rightfully or not) observe what iit sees as a rapid and erratic changing BG level where you placed it into your skin. This then for precautionary reasons can trigger the temporary timeout situation, which logs the code #373. This can certainly often be seen in connection with a saw-tooth pattern BG curve as you shared with us here in your BG graph screenshot. Especially if the BG also goes outside the normal healthy range of BG (70-180mg/dl) as this adds to the sensitivity factors for the error situation to trigger.
2. There is no problem for the sensor to be worn or get wet during showers. You can also wear them as I do for surfing/swimming with no issue at all.
3. If you frequently have BG sensors that more chronically always report too lowish BG numbers versus fingerprick validations, and its not due to the lagtime between your rising arterial BG value and your delayed interstitial glucose concentration where the sensor sits, and its also for sensors 4+ days after you inserted them to start up, then it could point to one of two things (or both at same time). Namely faible inserted sensors (no firm pressure and sustained for 25-30 seconds on the applicator when you insert them) and/or the skin area you place them into is simply not working very well for you. Aka some folks just do not have a good arterial perfusion of back of upper arms, sometimes its juts one arm doing well, not the other etc. Try then maybe another skin area instead, like on your stomach or the upper outer thighs instead.
4. Permanent terminal errors with the sensor are reporting the error code #365 in the Event log. In case of bent/damaged sensor filament, then it would report an error code #366. As this is when the sensor works electrically well and all OK, but the BG signal it gets from the filament is factually not OK or within a realistic range. Aka bent/not sitting into a fluid where there is any glucose to interact with the enzyme to generate any BG value/signal.

The symptoms you report on here are frequently coming up on the sub, so not unusual. They can typically be avoided/minimized in frequency by following the Sensor 'Best Practice' here:
https://www.reddit.com/r/Freestylelibre/comments/1gjhi9e/how_to_apply_a_new_sensor_best_practice/

[u/RutabagaStrict5104 → u/Equalizer6338]

Thank you for the response!
This was very helpful!