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Freestyle Libre Sensor: highly inaccurate??

Discussion in 'Blood Glucose Monitoring' started by TedTomato, Mar 4, 2018.

  1. ECDRUM

    ECDRUM Type 1 · Active Member

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    BG and interstitial glucose are not likely to be the same when taken at the same time. Interstitial will lag behind BG by 10 to 15 mins typically so if BG is rising it will read higher and if it is falling interstitial will read higher. This is however not a linear correlation and other factors such as activity level and local inflammation at the sensor site for the first few hours after application can all have effects. I find that when blood glucose is abnormally high or low Libre tends to exaggerate the effect in its readings and in these circumstances it is wise to do a BG test. I find the great value in Libre is in showing the direction of travel and the convenience of being able to scan 30 times a day or so to recognise trends and micromanage bolus injections to keep within normal parameters ( in my case I target staying within a range of 4 to 10 with a target average around 7). If I can achieve that this results in an HbA1c of about 6. Without Libre the best I could achieve was 8. It has been a game changer for me but it is not a total or direct replacement for finger prick testing: they measure different things and are not interchangeable.
     
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  2. Listlad

    Listlad Prediabetes · BANNED

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    Am plodding my way through this thread.

    Great post. Except I disagree with your (later) assertion that it is overkill for Prediabetics to use this device.
     
  3. Listlad

    Listlad Prediabetes · BANNED

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    Overkill for prediabetics ? Anything that will give frequent data points that relate to blood sugar levels will be beneficial to a Prediabetic. Or shouldnt we bothered about that?
     
  4. Scott-C

    Scott-C Type 1 · Well-Known Member

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    If it works for you, go for it!

    Reading the thread back, I was getting a tad annoyed with the op's attitude of more or less writing libre off as a waste of time and money after his huge experience of, erm, three sensors, despite several posters, including myself, pointing out ways of dealing with that, such as replacement, calibrating in his head, and calibrating through add ons and apps.
     
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  5. Listlad

    Listlad Prediabetes · BANNED

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    Okay. Understood.

    I can see it would be a useful tool for T2s and Prediabetics. Though I can see it might be particularly useful for T1s.
     
  6. Joesdad

    Joesdad Parent · Active Member

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    I'm a first time poster here.
    My son is 6 years old, diagnosed T1 in November 2018, and has been using the FS Libre for nearly 3 months now. Up to now they have generally been fine. On Thursday we changed the sensor 3 times, and the readings were 2-3 mml different to the blood prick readings. On the first one, we put it into the side of his arm and not the back. I read somewhere that if it goes into a muscle it will be inaccurate. So we changed it. The second one, there was a bleed when we applied the sensor, so we thought it was because of that. So we put a third one on, another bleed and again a difference of 2 to the blood test. We called Abbott and they suggested waiting 24-48 hours, after a bleed. So we are waiting, while in the meantime, can’t send him to school and expect teachers to do blood tests instead using a simple scanner. (Before anyone calls social services - He does have a careplan, and we and school keep to it rigidly, but we rely on the libre to make it work. DS's teachers are trained in doing blood checks but we don't want to drive him mad.)

    Have any of you ever had this experience? Firstly, how common is it to bleed when applying the sensor? Secondly, does a bleed affect the accuracy of the sensor? And, if bleeding does not affect it, we had three different sensors giving wild results!!

    The thing that is confusing us here, is that we've used probably 5 or 6 sensors to date, and they've all been fine. Now suddenly, we have 3 that are faulty?! For us, we don't want to finger prick a 6 year old constantly, the libre has been a lifesaver, but now we feel we are driving on a dark road without any lights, as we are giving food and don't know for certain where his levels are.
     
  7. deszcznocity

    deszcznocity Type 1 · Active Member

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    I have this all the time. You are inserting a foreign object to your childs body and the immune system kicks in, hence higher values than finger prick tests. The results settle in after 3-4 days. Also, whenever you take a shower - libre goes crazy. That is why I NEVER give myself any insulin based on Libre reading. I always do a finger prick test and then decide whether I require insulin or not. As for the bleeding part, yes, I do get bleeding occasionally. It does not affect the functionality. Again - you are inserting a sharp foreign object into your childs body. Last thing, after heavy intense physical exercise Libre also can go crazy. Always finger prick to be sure - saves you from going out of your mind. Hope this helps.
     
  8. kev-w

    kev-w Type 1 · Well-Known Member

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    With regards to the Libre, I'm about 18 months in using one on prescription, I'm quite happy to bolus from it usually, I swim and train a few times a week and can't fault its effectiveness, I have in years gone by finger pricked a finger on each hand and had 1.5mmol difference on my accucheck Aviva at the same time, and from talking to other T1's find they've seen similar, with regards to bleeding it's hit or miss, I've seen some folk say "bleeders are better readers" but I don't know, it's less accurate when the blood level is changing rapidly as the sensor sits in 'interstatial fluid (sp) which is under the skin on the outside of the muscle so doesn't directly read the capillary blood, and they do seem to like 12 hours to settle from insertion.

    Funny really in a non amusing way but my one week old sensor is probably the least accurate one I've had, I've a cold and trending a little high but yesterday I had an alarm go off telling me I was at 18mmol and a fingerstick said 12 and the closest it's been was 2mmol out so I'm going to blag the maker for a replacement and take it off a week early as it's a prescription item.
     
    #108 kev-w, Mar 6, 2020 at 2:37 PM
    Last edited: Mar 14, 2020
  9. Neonataldiabetes

    Neonataldiabetes Type 1 · Member

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    I get the full package, there's a scanner which collects all the 24 hour data, you can upload this to a cloud and share with your diabetes team, so no smart phone needed. :)
     
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  10. Kaycee

    Kaycee Type 1 · Newbie

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    Hi. My libre sensor is Mike's out. It says 5.2, but my finger prick meter tells me its 10.
    7, surely it should be that far out. I don't know what to do. I'm really confused as with everyone saying that the meter isn't a proper reading and could be faulty also the sensor could faulty as well. I mean, which is right.
     
  11. Tramk

    Tramk · Member

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    Hello, and welcome to the forum!
    Suggest you perform a comparison check. Guess you measure your blood sugar by fingerprick about 1,5 hours after meal. As you must give the Libre a little more time, 15 more minutes, and then compare the results. The numbers will probably not correspond, but after some time you will get the picture. If they deviate more than say 2-3 mmol/l during the week, you should probably make a telephone call to Libre. Good luck!
     
  12. Mr_Pot

    Mr_Pot Type 2 · Well-Known Member

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    I had a trial of the Libre 2 and discovered my bg stayed constant over most of the night. So I did a finger prick test in the middle of the night when any delay wouldn't make any difference and it read almost exactly the same as the Libre.
     
  13. Brunneria

    Brunneria Other · Guru
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    All you need to do is contact the Abbott helpline.
    They will ask you a few questions to establish that the sensor is malfunctioning, and then they send out another.
    It is very simple and easy.
     
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  14. Peter03

    Peter03 Type 1 · Well-Known Member

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    £64 sounds exspensive to me, I Don't use the libre anymore but they used to be €35 each I to found the libre inaccurate a lot of the time found it better with xdrip
     
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