Inaccurate Medtronic Guardian 4 sensors

[AJLang]

I've had three particular issues with the Guardian 4 sensors
a) a few weeks ago one reading 6.7 when actual BG was 3.4 but Guardian 4 was in a steady line. Fortunately I finger pricked and identified the hypo.
b) Thursday January 9th for 24 hours. Three sensors all did nothing but updating over a total of 24 hours. Phoned Medtronic and found that this was because the transmitter was out of warranty. It was exactly 365 days since I'd received that transmitter - I was surprised to say the least that as soon as it is out of warranty it stops working. I've got a new transmitter but had mistakenly assumed that the old one would keep working until it was no longer able to charge the sensors. Fortunately for that I'd put one of my remaining Libres on because
c) at 5am this morning BG a nice steady 7.5 on Medtronic sensor. Fortunately my Libre alarmed to say that I was much higher at 14! Three subsequent finger prick tests confirmed BGs around 14.
Not sure what to do about all of the above because it affects my confidence about the hybrid loop but when it does work it works brilliantly. I suppose my main concern if what if the Guardian 4 had mistakenly said that my level was much higher than it was and given me too much insulin.....
Any thoughts about any of this please?

 

[SB2015]

Hi Amanda
Sorry to read that you have these issues with the Guardian 4. I had the updating issue at times which was frustrating, but I got the impression that it did this whenever it was in any doubt, and put me back in manual. These sensors were always replaced. I don’t remember having the readings being wildly out. Good that you went with your symptoms and checked with a finger prick. I know @everydayupsanddowns had a similar issue recently.

I never got to the time out in a transmitter as I was in a contract which included replacement transmitters.
I wonder whether your DSN would switch you to Simplera Sync. This has an integrated transmitter so there is no charging issue and it is a lot easier putting in. Similar to Libre insertion. I am having a lot less ‘updating’ with these.

 

[everydayupsanddowns]

Yes I’ve found the Simpleras really good, though I’ve my second “Sensor Updating” error happening this morning 🙄

Not holding out much hope for the sensor.

Fortunately the app (WeCare) allows you to report the sensor failure and request a replacement if the updating lasts for several cycles.

 

[JohnWhi]

Transmitter warranty seems to be a strange thing. When I had a transmitter fail last year, I was told that Medtronic would not replace it as it was out of warranty, and I needed to ask the funding hospital to make a further 'treatment request'. Did that, and the replacement was issued, with a warranty only lasting to this month, when the pump warranty expires. From my experience, variations between sensor reading and BG can be significant. A frequent occurrence, if doing a finger-prick test before going to bed, is the alert that the calibration is not accepted, and that I need to wash my hands (though I did so before the test). In recent months, I have had the impression that SmartGuard Auto Correction has taken me lower than I would wish to be. Having said that, I think that HCL is working well, nearly all the time. Looking forward to the new pump software and Simplera.

 

[everydayupsanddowns]

Not holding out much hope for the sensor.

Unexpected positive update!

My Simplera sensor came to life after the first cycle of ‘Sensor updating’ and is currently tracking well.

The first experienced of ‘sensor updating’ was a bit frustrating, and resulted in a large proportion of a day being out of sensor coverage, and bouncing out of SmartGuard.

But this experience lets me know why they want you to wait for so many hours before reporting a failure, as some sensors clearly DO come back to life.

Hopefully I’ll be a bit more relaxed (and a bit less grumpy!) next time.

 

[SB2015]

That’s good to know @everydayupsanddowns . I have been given mixed messages. One person told me to replace if updating for more than three hours, another told me to wait for two cycles of updating. Could it be anything to do with fluctuating levels during the updating.

After a bit of a grump on my last one I still feel HCL trumps the hassles.
Hope this sensor continues to behave for you Mike.