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Freestyle Libre calibration

R

Rusty123

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I just got the freestyle libre for my sister (she's on disability and our region doesn't cover it)...she has had the discs and monitor for 1 month. Yesterday she wasn't feeling well (gastro) and called the ambulance. Her monitor was reading 15 but they did a pinprick and got 25! once in emerge same result, her's read 10 points lower than the pinprick. She just had her finger pricked again and her sugar is 10.9 but her freestyle libre read 4.9! has anyone had this occur? I've read that the machine does not need calibration but hers is way off consistently! i've called Abbott but after being on hold 65 minutes, hung up!

I'm thinking her machine is faulty but not sure...any advice is greatly appreciated!
 
There is a delay between interstitial fluid glucose levels and blood glucose levels but that sounds significant enough to be a faulty sensor......

Although I would imagine that some individuals just wont get the success that some others do, purely down to the way their body reacts.....

The best use for the Libre is for pattern spotting and basal testing...

From hearing others on here, replacement sensors are sent out without much fuss. so I would do that....
 
thanks, that's what I'll do!
 
Yesterday mine was telling me that I was 2.4 or LO or 2.2 I'm a non medicating T2 and I wasn't exercising.

11.17pm 2.8
11.21 (finger prick) 5.7
11.40 2.7

Just as an example. The finger prick was done on the same meter/reader.

However mine ALWAYS reads me mostly below 5 Generally in the 4's and sometimes in the 3's and if I check finger pricks are normally anything from 1.5 - 2.5 higher. So I've been adding 2 to whatever the Libre says I am.

Then I had an A1c and my Libre average glucose was pretty accurate i.e. .4 out. So I now take it's readings more seriously.

Also to be fair to the Libre the sensor has just fallen off so I think that it wasn't properly in yesterday and today.

Edited to add I've also never had the degree of mismatch that you are experiencing between the Libre and a finger prick.
 
novorapidboi26 said:
How useful has it been then for you as a non medicating T2...?

Do you intend to wear it as much as possible..?
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It's been brilliant for me. Once I got used to my readings being out.

It's portability - the fact that I can scan 2 hours after eating whilst also out walking. When out for meals I scan when the food is on the table and I'm about to start eating. The ease of using it meant that I could see what effects foods had on me and also for how long. That reinforced my low carb diet and stopped me from eating some things.

It helped me get my weight down and also lower my A1c. (which means no meds at the moment). By helping me with my diet I've also got ALL of my tests back into the normal bracket including my fatty liver.

I've learned that about the effects of illness, tooth extraction and just plain doing something different has on my bgl's. It's actually taught me loads about how my body works.

I don't intend to stop wearing it just yet as I'm now experimenting with adding foods back into my diet. If I can continue to control my bgl's then I think that in the future I will opt for finger prick testing every now and again.

I really wouldn't want to do what so many people have to and that finger prick test multiple times a day. If I have to then I will but while I have a choice my choice would be not to.
 
There is no doubt in my mind that the the downfall of the Libre system is the variation of results that you get between sensors. I have had a few that were very accurate according to comparison testing against my Abbott Freestyle Lite. I had one that red lined and the current one that reads three mmol/l higher than anything else I have.

I am going to have to evaluate the £50 per sensor against the rubbish some of them give out. I have one in stock and I will make my decision after trying that one. After all the one I have now might just be a one off.
 
Squire Fulwood said:
I am going to have to evaluate the £50 per sensor against the rubbish some of them give out. I have one in stock and I will make my decision after trying that one. After all the one I have now might just be a one off.
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I don't think Abbott likes those that read a lot higher as they could be dangerous for insulin users. I have only returned one for a replacement, and that was a high reader, although I was able to prove it as, coincidentally, I had fasting blood glucose test at the surgery when I was wearing one and was able to show that my FBG test of 5.4 was significantly lower than the Libre sensor had been all that morning.
 

Actually that happened to me when I went for my 2nd A1c (confirmation of diagnosis) Libre said 7.9 lab said 6.7. That's another + for me being able to scan just before having a blood test done.

But every sensor I've had since has read lower than a finger prick and tbh they have all been roughly the same lower. I did wonder when T1's started to use them en masse because I wasn't sure how they'd manage with the variation as it's so crucial for them to get it correct.
 
woodywhippet61 said:
Actually that happened to me when I went for my 2nd A1c (confirmation of diagnosis) Libre said 7.9 lab said 6.7. That's another + for me being able to scan just before having a blood test done.
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Ah! but did you continue scanning every 5 or 10 minutes for a period to make sure you had caught the time lag? I used my downloaded 15 minute log showing all the sensor readings from before, during, and several hours after my surgery test, all of which were significantly higher.
 
I also have had odd readings while using the libre v blood monitor in one case 8.2 libre v 18.1 blood glucose ( not one of my better readings ) but the difference really shocked me.
The low readings on the libre below 3 are incorrect as each time my actual bg is + 2-3 so the the 5-6 region (more like it).
Early days for me but very confusing for me at the moment
 
I agree with you I also have libre readings of 2.6 and on accu check 4.8.best to keep to.libre if u have always gone by that but its strange isnt it?
 
Madmaureen said:
I agree with you I also have libre readings of 2.6 and on accu check 4.8.best to keep to.libre if u have always gone by that but its strange isnt it?
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This is the problem I have had with the last 6 (?) sensors. Abbott even sent me a replacement meter to see if my meter was faulty but that did the same. I've checked results against Abbott's own blood testing strips for the libre and against another blood testing meter and I've allowed for the 10-15 minute interstitial delay... Both blood testing meters were close to each other, but the libre readings were low by 2-3 when my blood sugar is less than 6 and this is just too far out to be useful, particularly for overnight readings when my blood sugar just reads "LO" all night. And I really don't want to treat for hypos unless I actually have one.

As regards high readings, I've found it inaccurate (over reading?), but once my blood sugar is over 15 a small % change leads to a large absolute difference, and I'd be willing to do a blood test to quantify the problem. 10 lower than the pin prick is a worry, though.
 
It would be good if you could calibrate it by plotting a calibration curve in its memory. For me, my sensors always overread, but never by a percentage of the true value. At higher values, the percentage error is always greater than the percentage error at lower values.

Either way, I email Abbott for replacements. I've had two consecutive replacements no fuss, so try emailing.
 
Got to be a worry for T1s if there are doubts over the accuracy. Extent of problem might only become apparent after more widespread take up.
 

Get yourself a blucon transmitter from www.ambrosiasys.com for about 100 quid, download xDrip+ to your phone, allows you to calibrate, and get hypo alerts. Basically turns libre into full on cgm. Been using it for 3 months now. Provided I calibrate every 12 hours or so, the accuracy is vastly improved, frequently only about 0.2 or 0.3 out.
 

I'm well aware of Ambrossia's BluCon, I've been interested, but I'm going to wait until Ambrossia get their act together with deliveries, support and actual quality of the Nightrider at the moment. Plus, they're not delivering now until mid January
 
That's really interesting, but does it help when the libre reads LO?
 
EllieM said:
That's really interesting, but does it help when the libre reads LO?
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When the uncertainty is down to just 0.2 or 0.3, well then when it reads LO, it really means that you are LOW no matter!
- Get some sugar!

I think the neat feature about this setup with the blucon and using your iPhone like I do, is that you do get timely warnings when your Libre is measuring your bg is going below a preset value you have decided yourself to get alarms from. I may be a lucky fellow, because I have not experienced the bg readings being far off as others have reported on?
 
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