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Libre differences in readings

B

barb1

Active Member
I have been given a Libre system by UCLH as I have reactive hypoglycaemia and they want to check my levels throughout the next two weeks. I've had bariatric surgery and this condition is being seen in a small number of people.
I picked up the Libre last night and was told there is likely to be a 0.3 difference in the Libre and finger pricking test. However, this morning it said 3.2 on the Libre but was 4.8 on two different BG meters.
Has anyone else experienced quite such a difference?
 
Yes it's pretty normal. The advice given to me was it's not realtime, approx 15 mins behind. When I first got mine the libre readings were 2mmol higher but from reading on here the difference can be both ways. It took a couple of days to calibrate.

I use mine for the trends and the direction of the arrows rather than super accurate readings.
 
My experience was very similar to yours. I have no idea where the 0.3 different comes from - it is the first time I have read it to be quantified.

There are a few reasons for this: as @tiredoftrying2017 mentions, the Libre readings are about 15 minutes behind finger pricks; the Libre uses a different method to calculate BG so it will not provide exactly the same numbers; the Libre is calibrated in the factory not for your arm and putting something in your body will affect the readings far more than taking a bit of blood (I think this is why CGMs require calibration).

Whilst some people find they can rely on the Libre numbers, many focus on the trends and history.

Personally, I found the Libre to be furthest out when looking at high numbers (I think that is something about % difference). At the lower end, the difference may be due to calibration or delay.
 
Mine is always out by 1-2 when compared to a finger prick (agamatrix jazz). I've tested at 5 - 30 mins and it's NEVER been anything other 1-2 lower than the finger prick. Basically the time lag makes no difference for me. I've read on here that the meter that I use for finger pricking tends to read to high. I find the lack of accuracy frustrating. But it is very useful when it comes to checking what effect meals and exercise etc have on my bg.

I'll know more once I've had my A1c.
 
@barb1 , if you activated the sensor shortly after inserting, it'll normally be out by quite a bit till the small amount of damage caused by the needle going in and out settles down a bit. Readings ought to tighten up in a day or two. It's why a lot of people insert it then wait a day or two before activating it, to save getting duff readings on the first day or two.
 
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