Freestyle libre variance

lely

lely

Well-Known Member
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208
Hi All. I just started my 2 week trial for the freestyle libre today.
I'm sure I'm gonna have lots of puzzled moments to work though.
The 1st. The variance.
The finger prick is the true test, correct?
And there is a delay I'm the test result for the libre, correct?
Suggesting to me that if I had a test from my finger then the read from the libre would follow that patten 10 minutes or so later.
I know my BG should be falling at the moment as there is insulin on board and no food eaten since 7.30. (Providing my basal is steady). But my reading is finger 13.2 and libre 8.3.
Any explanation welcome.
 
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When you say you have just started, do you mean you have started today?
The reason I ask is our bodies get a little upset when we insert something and takes a while to get used to it. For some people, this is just a few hours and for others this could be about 24 hours. As a result of this "distress" around the sensor, when first inserted, the results are not very reliable.

Once the results have settled down, you are likely to continue to see a variation compared to your finger prick. As you say, this is partially related to the delay but also because it is using a different method for calculation and it is calibrated in the factory ... so not to your body.
For this reason, a finger prick is the most accurate reading and is the only reading accepted by the DVLA and recommended by many healthcare professionals for calculating insulin doses.
However, this is not to downplay the value of the Libre (and other CGMs). The biggest value from the Libre is the history and the trends. I liken using a Libre just to replace finger pricks to using a smart phone to just make phone calls.

I sometime blog for Diabetes UK. When the announcement was made about the Libre, they asked me to write a post about it. I tried to explain the points above (and a bit more) in this post.
 
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Shannon27

Shannon27

Well-Known Member
Messages
290
Type of diabetes
Type 1
Treatment type
Insulin
lely said:
Hi All. I just started my 2 week trial for the freestyle libre today.
I'm sure I'm gonna have lots of puzzled moments to work though.
The 1st. The variance.
The finger prick is the true test, correct?
And there is a delay I'm the test result for the libre, correct?
Suggesting to me that if I had a test from my finger then the read from the libre would follow that patten 10 minutes or so later.
I know my BG should be falling at the moment as there is insulin on board and no food eaten since 7.30. (Providing my basal is steady). But my reading is finger 13.2 and libre 8.3.
Any explanation welcome.
Click to expand...

I would always go by the BG test for the first 2 days, as the Libre needs time to acclimatise to your body. It's very annoying, but after that it was spot on for me!
 
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smag3

smag3

Well-Known Member
Messages
104
Type of diabetes
Type 1
Treatment type
Insulin
Dislikes
Doctors telling me that I probably know more than them
I agree with Shannon. I now put new sensor in place but don't activate it, 24 hours before it is due to be activated. Does mean you are wearing 2 for 24 hours but not really an issue. I have been using mine for 3 years now and rely on it totally. Very rarely do a finger prick.
 
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isjoberg

Well-Known Member
Messages
268
Type of diabetes
Type 1
The ends of the scale (e.g. really low or really high) the bg meter is decreasingly accurate, so I personally don't always rely on my bg being the 'exact' number, but as an indicator of the area that my bg is in.
Here is a really well explained discussion on bg variation! Not sure if you have to join the fb group to see it but worthwhile!! https://www.facebook.com/notes/abbo...arisons-with-bgm-and-errors/1524464310953693/

And here is another article: https://diatribe.org/are-blood-glucose-meters-accurate-new-data-18-meters
 
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