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Freestyle Libre readings

Discussion in 'Blood Glucose Monitoring' started by Postleneo, Nov 30, 2016.

  1. Postleneo

    Postleneo Type 1 · Well-Known Member

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    Hi guys - was wondering if any Freestyle Libre users experienced the following??..... Was given a freestyle libre yesterday and basically rushed home to set it up and start using so as to save my finger tips dying a slow and painful death!! After following the instructions to the letter and waiting 60 minutes for the sensor to activate i scanned my first reading so as to compare with my blood gucose meter. Readings were as follows - Libre-4.7 glucose meter 5.2, 30 mins later Libra 3.5 glucose metre 5, again another 30 mins later Libre 3.1 Meter 5.... one more 30 mins later lebre LO meter 5.1. I have since been comparing and today whilst insulin is on board there seems to be on average 1.5 - 2 mmol diferrence - either high or low but when no insulin on boad libre readings have been only .3 mmol out!?! - Was wondering wether or not it takes a few days to start correctly working or is it that the sensor is faulty?? any thoughts would be appreciated. Thanks guys :)
     
  2. Bluetit1802

    Bluetit1802 Type 2 (in remission!) · Legend

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    Many of us find it is better to wait at least 24 hours before activating to allow time for your body to accept a foreign object in your arm. I personally find the first 12 hours after activation the sensor is still settling down and I get lower readings.
    Also, are you scanning then testing around 15 minutes later? The interstitial fluid that the sensor measures is about 10 to 15 minutes behind our capillary blood.

    I don't use insulin so can't comment on how that affects matters.
     
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  3. slip

    slip Type 1 · Well-Known Member

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    so much for saving your finger tips!

    As already mentioned it can take ~24hrs to settle in and that there's a slight delay between measurements types. I can't say I've noticed IOB making a difference to the accuracy - next time I use a sensor I'll try and keep track of that, but I might suggest that having IOB could mean your BS levels are changing and the sensors algorithms are having issues with the 'rapid' changings levels? Hope it settles down and you can rely on it a bit more given time. We need a new 'smiley' for battered fingers!
     
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  4. Energize

    Energize Type 2 · Well-Known Member

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    Hi

    As already mentiioned, the sensors seem to be more accurate if applied 12-24 hours before activating. That's my experience, certainly.

    Also, comparing the results of devices, be it a variety of glucometers, Libre or whatever else, there will likely be a difference. There are lots of variables - the meters themselves, even if same make/model, each test strip can produce a different result, a new tub of test strips can produce a different result. It's quite likely to produce a different reading if you were to test the same blood from a finger prick on different test strips/meters etc.

    With the Libre, it takes the interstitial fluid a bit longer to change up or down as per the glucose level in the blood, especially when the blood glucose is changing quickly.

    There is also an acceptable range for any difference (sorry, can't quote the figures)

    So, in view of your results so far, I would say you are getting pretty good readings from the Libre, on the whole. The high and low readings are likely to be a bit more extreme than a glucometer but, again, this is normal and acceptable.

    I hope you get to like the Libre system - most become 'addicted' ;)
     
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  5. flashgordon12345

    flashgordon12345 · Member

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    HI, I bought this and its a great bit of kit, but im here about how inaccurate the reading are.
    Ive had mine in for 24 hours.
    Everytime I test my back of arm with sensor its about 2.0mmol lower then my finger, I thought maybe its because my finger is futher then my back of arm, but i tested my arm next to the sensor and it gave a reading 1.0mmol higher?! Also it takes about 5-10minutres for the machine to get the numbers its not instant.
    WHAT IS GOING ON!
     
  6. Bluetit1802

    Bluetit1802 Type 2 (in remission!) · Legend

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    The Libre measures the glucose in the interstitial fluid (the fluid that runs under the skin). It does not use blood. The finger pricker measures the blood in your capillary veins. They are not measuring the same thing, so how far your fingers are from the sensor is irrelevant. Also, our interstitial fluid takes longer to "soak up" the glucose - it runs about 10 to 15 minutes behind the capillaries. If you are doing comparison tests you need to scan, wait 10 to 15 minutes, then finger prick. Also, if your blood glucose is spiking up rapidly or coming down rapidly, the sensor won't be as accurate.
     
  7. Postleneo

    Postleneo Type 1 · Well-Known Member

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    Cheers guys... been now just over 48 hours and readings seem to have levelled out... number of check today were bob on with my glucose meter readings most others were only no more than . 5 mmol out either side.... other than just recently where the libra is 1mmol lower but have just had a fairly warm bath!!... this carries on think will have to somehow find the cash each month to totally convert and use libre on a permanent full time basis!! Only have two hopes now... 1.. the Libre sensors will become available on the NHS .. and 2... Not been accidentally scanned at Morrisons and be mistaken for a cabbage!!:D
     
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  8. Energize

    Energize Type 2 · Well-Known Member

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    [QUOTE="Postleneo, post: 1321069, member: 260061" .. and 2... Not been accidentally scanned at Morrisons and be mistaken for a cabbage!!:D[/QUOTE]
    This had me laughing ... Great sense of humour :)
    Thanks :)
     
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