• Guest - w'd love to know what you think about the forum! Take the 2025 Survey »

2 CGM’s & 2 very different readings!

Vix85

Active Member
Messages
25
Location
Kent
Type of diabetes
Type 1
Treatment type
Insulin
Morning!

I’ve recently started with the Medtronic 780g which in itself is a learning curve!

However, I’m still wearing my libre and the discrepancies I’m getting from my libre vs my G4 sensor are huge!

G4 - 8.2
Libre - 13.2

Huge discrepancies! And I’ve don’t a finger stick test and it’s closer to the libre

Anyone else experienced this??
I want to just use my Medtronic equipment but I have serious trust issues with it, and the sensors in my experience are only lasting 3 days max.

Thanks x
 
I am using my first Libre 2 and I am happy, went twice to the lab and the results prooved it a good match with the lab.
 
Ronancastled said:
A finger prick should settle it
Click to expand...

Dont think so!!!! Was using a Contour Next before and going to Lab every week due to not trusting results.

"Lab" to "Contour next"comparison:

4.6 - 5.7 (dif: 1.1)
4.8 - 6.8 (dif: 2.0)
5.8 - 8.0 (dif: 2.2)
 
@Vix85 when did you apply your CGMs?
The Medtronic may require some "bedding in".
That said, variations should not be taken as absolute numbers but as percentages. Accuracy is measured this way and explains large discrepancy at high numbers.
 
In Response said:
@Vix85 when did you apply your CGMs?
The Medtronic may require some "bedding in".
That said, variations should not be taken as absolute numbers but as percentages. Accuracy is measured this way and explains large discrepancy at high numbers.
Click to expand...

It’s big differences!

G4 - 8.2
Libre - 13.2
Finger prick - 10.2

It doesn’t calibrate either, just drops back down on the meter!
 
Going by the above the G4 is closer to your finger prick than the Libre is. I was always told never to compare different CGM’s though as you can get varying results as they work in different ways. You also have to remember that CGM’s don’t measure blood they measure fluid between the cells so can sometimes be 15 minutes behind “real” blood sugar results.

Even though you don’t need to calibrate the G4 officially I still calibrate mine twice a day and don’t find it’s too far out for the majority of the time.
 
Vix85 said:
It’s big differences!

G4 - 8.2
Libre - 13.2
Finger prick - 10.2

It doesn’t calibrate either, just drops back down on the meter!
Click to expand...
CGMs are designed to be most accurate at "normal" levels and only state their accuracy to 15%. So, if your finger prick is 100% accurate (which it is not designed to be), you could get readings between 8.5 and 11.5. Neither are very far out under this consideration.

Above 10, they are renowned to be less accurate and unreliable. Hence the advice to check highs (and lows) with finger pricker before correcting.
You did not mention when you applied your Medtronic sensor. I have not used that CGM but found Libre made up numbers if I started it the day I applied it as my body needed time to get used to the alien object in my arm. I had zero expectations of any accuracy for the first 24 hours of I started it the day I applied it l.

If you are not happy with the Medtronic sensor considering the known limitations of CGMs, you need to contact Medtronic.
 
Not sure how long you’ve been using the new pump and sensors but I found mine took a good few days to “settle”. I’m two weeks in now and it’s pretty close to what the finger prick is saying (unless they are falling or rising rapidly in which case there is a bit of a lag)
 
Hi please can someone advise I started in the guardian 4 sensor yesterday, since midnight it has alerted me of a low, this am at 5 it started again to the point I got up & did a bm- 8.5 (the guardian said I was 3.6) really confused? Should I get hold of my nurse
Clearly this isn’t right
Many thanks
 
@,jess1d is it possible that you laid on your sensor?
I ask because a "feature" of CGMs is a risk of "compression lows". This is where the sensor reports a false low when pressure is applied. This is most likely to occur at night when we lie on it accidentally.
 

I did wonder this after posting
thanks
hopefully yes
I only started it yesterday lunchtime but gotta say very pleased with it so far
 
I have had many many issues with libre two was promised libre three a year ago ended up going to dexcom but had app issues with that so team put me back on libre two which im having major issues with always loosing signal failing cannot read when im in a low blood sugar etc ive requested to go to the same insulin device and sensor as your self as seem to have an overall better working standard than the rest other than dexcom g6 but my team wont allow me to have that because im over 30 im 45 with six children two dogs a very busy life style always rely on a finger prick of unsure of results on sensors
 
I find if I am lay down in bed and take a reading ( either cgm or bg) then stand up. The sugar level rises by about 1.5 within a 2 or 3 minutes. This is our bodies response to waking and standing. The body knows it is going to need more energy, so releases a small amount into the blood.
 
Sorry I'm a bit confused why the hospital team won't allow you to have the Medtronic pump and sensor @blowinbubbles77 Have I read it wrong, or are you saying it's because of your age, because people a lot older than 45 are using it.
 
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn More.…