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Wrong readings with freestyle libre 2

Bails112

Member
I wanted to know if anyone else has been going through this or has gone through this, so yesterday evening i tested my blood on the sensor it was saying 10.0 I gave my insulin for my food and carried on with my night, before I went to bed I test my blood a few times just to make sure and the sensor was saying 7.0 so I went to prick myself to test my blood on the metre and the metre was saying 14.0!

That is a big difference and I was shocked with how it was that high, in these circumstances which device would you trust the most, as it has really made me worried about my readings on the sensor being wrong when my sensor has been saying my blood has been in range for weeks.
I am trying to understand why it was such a big gap and this carried on for a few hours like this, are the sensors known for being slow or are they more reliable than pricking yourself?
 
The advice from my doctors and nurses is to trust the finger prick. If I'm in the middle (say 6 to 7) I just trust my libre. If I'm low I trust the finger prick because of the lag (I am often lower than what my libre says). Highs I don't worry so much about because I've only had one high but there's still a lag, as I understand it: interstitual BGL is never going to match exactly capillary. Something to ask about with your professionals?
 
How long did you wear this sensor?

I myself started using them around march 2021 and found them excellent at the time. That is until the same period last year.
They would start good, pretty close to finger pricks, but after around a week they started to deviate. The deviation gets worse every day until they just stop working according to the app.
The trouble is that, like you I assume, I don't prick very often if at all so at first I thought I was just doing great! After a couple months of not wearing a sensor I applied one 2 weeks ago and same story. 4 days before the end it stopped (after indication lower and lower readings for about 3 days).
Of the last 12 sensors only one made it a full 14 days and coincidence or not, it was the only one I got as a replacement for one that stopped after just a few days.
Nowadays, if I wear one at all, I do a finger prick if I'm doing better or worse than I expect. But that also defeats the purpose for me.
 
If I get a really low reading I finger test. For example I had an warning saying in was at 3 but finger pricked and it read 5.9. I always prick now with a low reading on the Libre2 before taking action as I treated a low to find out I want low and then had a really high reading because I treated when I didn’t need to. Frustrating but I am getting used to it now.
 
Currently experiencing L2 inaccuracy issue of up to 40% out cf finger prick, particularly at the lower end. I am being careful to do a finger prick test first & scan L2 10-15 minutes later to take the lag between CBG & ISF into account. The product specification for both L2 & finger prick meters is to be within 15%, so when comparing to each other there is a potential tolerance of up to 17.25%. At up to 40% under true readings the alarm is often going off telling me I am having a hypo, when I'm not. I contacted Abbott who advised to swap the sensor & they will send a replacement. This has not resolved the issue. I have been using L2 for about a year. I did a lot of parallel finger pricks to validate the sensors worked & they were usually within about 5%, so I reduced second checks. The recent increase in L2 hypo alarms made me think & delve deeper again. My concern is that Abbott have adjusted their algorithm in response to the recent recall, when a batch of sensors was found to be reading too high, but have swung the pendulum a little too far. Of course only Abbott or the MHRA will have enough visibility to know this. Has anyone else just started to have this problem? We should adapt to evolve to accommodate the tech, it should perform according to its spec or consider switching to a different sensor/manufacturer.

Wrt the other points in this discussion: I find if I put a new sensor on after a shower & also prep the area with an alcohol swab & let then skin dry, they stick on for the duration. I usually put my new sensors on in the morning, have 2 sensors in place for the day & then when my older one expires, that evening, the new one has 'soaked' & is ready to go. Some have fallen off but mostly on a hot, humid summers day following a run. One sensor has failed, it would not read. Error message read 'Scanning error. Try again in 10 minutes', which happens sometimes. This happened for half an hour so I called Abbott & they advised to swap & they would replace.

If anyone has direct experience of using both L2 & L3, it would be great to hear how they compare, especially accuracy. Likewise, if anyone has first hand experience of a G7 plus L2/3.

Best of luck.
 

Hi, if this takes place at night, there is a known issue called compression lows. This is when you are sleeping and load your body weight into the device... giving a temporary very low reading. Look for a video on youtube named:

"FreeStyle Libre 2 | My Honest Review after 2 Years", by "Type One Talks"

He explains this...
 
Hello, thanks for the answer but it is during the day. I was only able to spot the difference by comparing with finger prick tests. After a run of 3 "bad" sensors the 4th is working accurately.
 
I have been using Libre 2 for about 8 months and am becoming disillusioned with it. I am Type 2 diagnosed one year ago, have my HbA1c down to 41 and pay for these things myself.

Unlike most folk on here, my readings with the sensor tend to go far higher than a finger prick reading. I have just had 9.2 on sensor with finger prick 5.5. At the other extreme I have had a number of sensor readings between 3 and 4 but never had a finger prick reading below 4.4

Abbott have replaced about 5 sensors for me when I have rung to complain and there is never an issue with them doing this. However, I am just wondering whether they offer me any accuracy at all for approximately £24 per week.

I am sure Abbot will keep replacing them without question as they want me to keep buying.
 
Hello, I am currently swopping from the l2 to the guardian 4 cgm. I am running the 2 side by side to check the new sensor is not doing anything silly. The guardian 4 is working with my pump and is automatically bolusing of the info given by sensor.

I can be showing low on one sensor normal on another and also the same with highs. One can show 12 and the other can show 17.

Can get very confusing.


I would say around 75% of the time they are both similar.

This weekend I have had 2 l2 fail, have not had many issues with this in the past. Just get the unable to read error, try again in 10mins fairly often.
 
I've been given a trial on simbionics sensor.
It seemed OK when it started however today it showed me as being 6.6. (Not eaten for 24 hours and only drank water). Out of curiosity I tried the finger prick test on my left hand and it said I was at 15. I thought that seemed odd as I am not feeling any of the sickness or blurred vision I normally get when it goes high so I checked with my right hand. That one says it is 19.5. Very big discrepancies.
 
Did you ever get this issue resolved, I seem to be having the same problem?
 
Some sensors don't work well, most do. I've just got rid of a sensor that was consistently over-reading my 2.5 mmol/l. Last year I had a couple of sensors which were overreading by ~5 mmol/l. They are certainly better than they used to be (and they now give up and tell you to replace them more often than not) but there are still failures.
 
Had trouble with a couple of sensors over the last few years but have to say I like them overal
 
I am new at libra, but already have two that stop work, and now for 3 days, readings are pretty high. Looks like insulin make no difference.
 
I have used the Libre 2 for 4 sensors now, so 2 months. Very happy with them. Yesterday I tried the Libre 2 PLUS sensor as it would appear to be an updated model. It also does 15 days rather than 14.
I woke (normally) this morning with a reading of 3.9 which over then next half hour dropped to 2.9. Obviously I finger pricked the moment I saw the reading, and got a 5.6 reading. I did a 2nd finger prick at 2.9 and still had a 5.6 reading.
This is my first 24 hours using the L2PLUS and I have already totally lost faith in it. Its been massively low reading all day and I am now showing 3.1 on the reader and prick tests show me consistently at 5.8.
I will contact Abbott tomorrow and see what they suggest. I bought 4 of the L2PLUS and now wish I had stayed on the old ones.
Anyone else used the PLUS version?
Should I remove the current sensor and try a new one? I pay for them myself and dont want to waste £50 if Abbot wont refund it because I "took it off".
 
I haven't yet tried a PLUS, but do always wait at least 24 after putting a libre on before taking any readings. Although the pack says wait an hour, many of us find it takes much longer to be accurate.
So I'd say wait until tomorrow, if it hasn't settled call them. They will probably replace, for free
 
I'm wearing my 2nd Libre 2 Plus right now, have been taking some control readings and for me Libre 2 Plus seems to be closer to glucometer readings (using Libre 2 reader with strips) than Libre 2. The precision seems to be better at low to normal range and seeing bigger discrepancies at higher BG readings. It does take about a day for my sensors to settle in. I promised to post my comparisons in another thread I've been using - I will try and provide an update with my measurements over this weekend.
 
It's a general feature of the technology that sometimes sensors need time to "bed in" because a new sensor can irritate the tissue around it and make it read low. So I wouldn't give up on a sensor till I had worn it for 24 hours.

(Based on my experience with dexcom, where I pre insert by 12 hours before activation and so avoid the issue. I believe that all cgms sometimes have this issue but happy to be corrected.)
 
With your next sensor, put on 24 hours before activation. I find that helps enormously with accuracy. The first few hours after activation are still a little dodgy but do settle. My first day is spent doing lots of blood tests until I feel it is working ok. I then only use a couple of strips throughout its life until the last few hours when I feel accuracy dips again.
 
I've now posted my results from round two of testing Libre 2 vs Libre 2 Plus: https://www.diabetes.co.uk/forum/threads/libre-2-plus.203561/
 
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