Hba1c - Freestyle Libre 2 and how accurate is the estimated A1c

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OwlyT

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Type 2
Hello, my first time posting!

I have just started using a Freestyle Libre 2 and wondered how accurate is the A1c estimation against blood tests?
 
In my experience the Libre "estimated' HBA1c is consistently inaccurate.
On the couple of occasions I compared them, Libre has report 10 less than my blood test.

It is probably a useful measure to track progress but do not consider it to be the same as the true blood HBA1C.
 
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I found it quite wrong.
mySugr plus finger pricks was more accurate.
 
I found to be very innacurrate in the second week of wearing each sensor so gave up. Usually my finger prick sensor readings Hba1c estmate is just a little above the actual blood test Hba1c result and i know this is because my BG drops overnight and obviously dont test whilst asleep.
 
I find it is usually fairly consistently 3-5 mmols/mol lower than my actual blood reading.
If you are only just starting to use Libre then the estimated HbA1c has less data to go on so will be less accurate. Over 90 day usage, I think it is likely to be a bit more reliable....but still just as a guide.... so don't take it at face value. Most people seem to find their actual result will be a bit higher, particularly if you get lots of compression lows during the night.
 
helli said:
In my experience the Libre "estimated' HBA1c is consistently inaccurate.
On the couple of occasions I compared them, Libre has report 10 less than my blood test.

It is probably a useful measure to track progress to track but do not consider it to be the same as the true blood HBA1C.
Click to expand...
harbottle said:
I found it quite wrong.
mySugr plus finger pricks was more accurate.
Click to expand...
I too find it is out for me and I have been using the Libre for years.
 
The Libre reports me as hypo so many times when I'm not according to my BG monitor cos Yes I always check, it always tells me my HbA1c will be lower than it really is. It's designed to be accurate between 4.0 and 10.0. But it isn't. For me anyway. Some sensors are cock on within tenths of a mmol, but some really aren't anywhere like that reliable. No way with either Libre 1 or 2 (although the 2 are usually a bit nearer fingerpricks) could I rely on the sensors to base insulin jabs on.
 
Just tested BG on meter 8.6 and bolused for lunch. Libre says 6.8.
 
For me the Libre is usually spot on accurate and I barely finger prick any more, just once or twice after changing sensor to verify accuracy. I use it to dose with no worries. As others have said, it does need 90 days records to predict Hba1c. Mine predicted 50 and it was 51.

I think I am lucky in as much as I get on with it so well.
 
@OwlyT are you asking about the accuracy of the spot readings form the LIbre compared to finger pricks?
Or, are you asking about the accuracy of the estimated HBA1C that the Libre provides?

I think there seems to be a confusion based on the responses above.

You also need to take into consideration the known limitations of using a CGM.
 
I find my Libre 2 HBA1C is a lot higher than the actual blood test. Recently it was 54mmol versus 58 mmol on my Libre
 
I recently had an HbA1c result of 52 and the libre seems to lag behind. It predicted around 55 at the time of the test, then dropped to 51 about 3 weeks later. It is currently estimating 55, but I went on holiday a couple of weeks ago, had a massive asthma attack in very warm weather and ended up on a nebuliser and oral steroids. That medication unsurprisingly sent my sugars through the roof for about 10 days and ruined my TIR for a while. So I would expect an impact on the Libre’s estimate, and it’s a helpful trend indicator while I would agree that it can’t replace the blood test. My DSN told me that there is currently a trial going on looking at the accuracy of the libre’s HbA1c estimate.
 
My body doesn’t seem to recognise the conversion formula they use (which is only a ’best fit’ estimate based on historic paired data sets).

Libre always underestimated my HbA1c.

Dexcom Clarity seems to do a little better.
 
I got fed up with how different the readings of my Libre 2 and the finger prick test were for normal day-to-day monitoring, so stopped using the finger prick test. I only do a finger prick test if my Libre 2 is reading too low or too high and I'm concerned about it. I am much more relaxed since doing this. I am not expecting my HbA1c to be accurate when I have my review in August.
 
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