Freestyle libre 2 failures very annoying

[lilyb]

To suddenly be told on my phone that sensor has failed and to replace immediately is disconcerting luckily on both occasions I have had a replacement on hand.
Bit fed up because the first one had only been on for 4 days and the second for 6 days.
Does anyone else get woken up with an alarm for hypo’s because of the way they sleep?

 

[rebrascora]

The false alarms through the night are what we call "compression lows" where you lie on the arm with the sensor. You can mostly overcome this by 1. placing the sensor more towards the back of the arm and 2. developing a habit of lying with your other hand under the arm with the sensor on it when you lie on that side to lift the are/sensor up off the mattress a little bit. The latter may sound complicated but you can learn to do it, particularly if you go to sleep on that side regularly. Your body still has spatial awareness whilst you sleep which is why you don't fall out of bed or roll into your partner, even in a strange bed like in a hotel room.

As regards the sensors failing early, my guess would be that they have started to come loose perhaps on one side and the filament which samples your interstitial fluid can become kinked if the sensor is not fully secure. This then prevents it from working correctly. Good skin prep is really important and I also use an arm strap after application to support and protect my sensor particularly during the first couple of days to give it the opportunity to form a really good bond with my skin. It also serves to remind me which arm my sensor is on when I get in the shower or towel dry afterwards as I have been known to scrub a sensor off during those activities because I simply forgot it was there.

If you contact the Customer services at Abbott they will replace your failed sensors. The NHS should not fund faulty items so it is your responsibility to report them to the manufacturer and get replacements and Abbott are very good about replacing them. You can do it via the phoneline or there is an online form and you may be expected to return the failed sensors, for which they will send you prepaid postage, so don't throw them out.

 

[Chris27]

Can I ask Barbara (or others) about a similar problem? I was diagnosed about 18 months ago and since then have had periodic problems with sensors which either under-record or over-record. My present sensor, which I applied before breakfast (ie fasting) showed 9.2 against a prick reading of 5.2. It has settled down a bit, but I guess is systematically 1 or 2 above the correct reading. I can do the mental arithmetic, but it messes up the statistics (which of course go to my consultant).

The previous sensor under-recorded by a similar amount. The problem there is that the alarm wakes me up at night and the prick test confirms that I am not having a hypo.

Could this be anything to do with where I am placing the sensor? To avoid compression lows I apply it slightly under my arm, where the skin is looser (and it is loose, as I am nearly 80).

Should I be reporting these to Abbott as defective? Will they replace in these circumstances?

 

[rebrascora]

Can I ask Barbara (or others) about a similar problem? I was diagnosed about 18 months ago and since then have had periodic problems with sensors which either under-record or over-record. My present sensor, which I applied before breakfast (ie fasting) showed 9.2 against a prick reading of 5.2. It has settled down a bit, but I guess is systematically 1 or 2 above the correct reading. I can do the mental arithmetic, but it messes up the statistics (which of course go to my consultant).

The previous sensor under-recorded by a similar amount. The problem there is that the alarm wakes me up at night and the prick test confirms that I am not having a hypo.

Could this be anything to do with where I am placing the sensor? To avoid compression lows I apply it slightly under my arm, where the skin is looser (and it is loose, as I am nearly 80).

Should I be reporting these to Abbott as defective? Will they replace in these circumstances?

Generally they will replace them if you have 3 readings which are more than 2mmols astray from comparison finger pricks.

My Libre sensors always read lower than my Caresens BG meter usually by about 1mmol which I am fine with but having tried a couple of other BG meters, I suspect my Caresens reads slightly high. I bought some Freestyle Optium test strips to try in my Libre reader and interestingly they almost always read a tiny fraction lower than the Libre sensor, but I trust my Caresens BG meter as I have used that the longest and it was officially supplied by the hospital. That said the Libre being mostly just 1mmol out is fine with me as that is close enough and I generally just go with my Libre result.
As regards things being a bit astray or not consistent in the first day or so, many of us find that applying the new sensor a day before the old one expires and giving our body 24 hours to react to it can help with getting more reliable results from the start. So we apply the new sensor a day early but don't activate it until the old one expires. Whilst the sensor filament is obviously sterile, our tissue can still react to a foreign body suddenly being "fired" into it. @helli refers to this as insertion trauma which I think is a really good term to describe it. Some people's bodies react more strongly to this than others but many of us find it is worth forward planning and giving it that extra day to bed in before we activate it, to get more reliable results.

Another thing which will impact the Libre readings is hydration and if you are dehydrated which can easily happen at this time of year and particularly as you get older and generally it will cause Libre to read higher than BG if you are a bit dehydrated. There are times when I have come in the house on an evening and drunk a glass of something cool and my levels have suddenly dropped 2mmols and I am sure that is due to rehydration, so worth keeping that in mind if you are getting higher readings than your finger prick.

As regards compression lows during the night, siting the sensor to minimize the risk of this is important, so more towards the back of the arm than the side (be it inside or outside). The wight of your arm on the sensor is not particularly a problem if you sleep on your back, it is more your body weight when you lie on one side or the other. Try lying down on your side in bed and feel where the sensor is and if your weight is pressing it into the mattress and then work out if you need it further forward or backward to reduce that pressure. I have also developed a way of sleeping on the sensor arm with the hand of the other arm under the sensor arm just above the elbow which lifts the sensor up off the mattress a bit. I have gradually made this sleeping position a habit and it is surprisingly comfortable, kind of like giving yourself a hug with the Libre arm uppermost. I believe @Inka has independently also developed a similar posture to prevent compression lows and also finds it works. If you have the sensor too much to the inside it will likely be compressed by your ribs so finding a good spot is important.

As regards having loose skin I apply my sensor with my hand on my shoulder which tends to tighten up loose skin. I think this is important for the insertion process as much as how the sensor works afterwards. Taut skin will allow the needle carrying the filament to go through it more cleanly and easily as well as meaning that the adhesive will be attaching to smooth unwrinkled skin which will therefore allow better adhesion. I stand with the hand of the arm that the senor is going to be applied to on my opposite shoulder and looking in the mirror, I reach underneath with the applicator and apply it where I know it needs to be. I also hold it for a count of 100 before I wriggle the applicator free as that gives the adhesive a bit of time to form a bond with my skin and the applicator rarely comes away cleanly so giving it that bit of time and then gently wriggling it until it comes away, helps prevent lifting the sensor and disturbing or kinking the filament which can lead to sensor failure.

 

[helli]

I was recently advised to make sure I had sufficient fat for the filament to go into.
In my case, my arm is pretty lean in places and definitely more muscle than fat. As a result, I have changed my sensor placement and the accuracy has significantly improved.
However, I do not know how this "rule" applies when you have loose skin. It is possible that the sensor is not going into fat?

 

[Chris27]

Generally they will replace them if you have 3 readings which are more than 2mmols astray from comparison finger pricks.

My Libre sensors always read lower than my Caresens BG meter usually by about 1mmol which I am fine with but having tried a couple of other BG meters, I suspect my Caresens reads slightly high. I bought some Freestyle Optium test strips to try in my Libre reader and interestingly they almost always read a tiny fraction lower than the Libre sensor, but I trust my Caresens BG meter as I have used that the longest and it was officially supplied by the hospital. That said the Libre being mostly just 1mmol out is fine with me as that is close enough and I generally just go with my Libre result.
As regards things being a bit astray or not consistent in the first day or so, many of us find that applying the new sensor a day before the old one expires and giving our body 24 hours to react to it can help with getting more reliable results from the start. So we apply the new sensor a day early but don't activate it until the old one expires. Whilst the sensor filament is obviously sterile, our tissue can still react to a foreign body suddenly being "fired" into it. @helli refers to this as insertion trauma which I think is a really good term to describe it. Some people's bodies react more strongly to this than others but many of us find it is worth forward planning and giving it that extra day to bed in before we activate it, to get more reliable results.

Another thing which will impact the Libre readings is hydration and if you are dehydrated which can easily happen at this time of year and particularly as you get older and generally it will cause Libre to read higher than BG if you are a bit dehydrated. There are times when I have come in the house on an evening and drunk a glass of something cool and my levels have suddenly dropped 2mmols and I am sure that is due to rehydration, so worth keeping that in mind if you are getting higher readings than your finger prick.

As regards compression lows during the night, siting the sensor to minimize the risk of this is important, so more towards the back of the arm than the side (be it inside or outside). The wight of your arm on the sensor is not particularly a problem if you sleep on your back, it is more your body weight when you lie on one side or the other. Try lying down on your side in bed and feel where the sensor is and if your weight is pressing it into the mattress and then work out if you need it further forward or backward to reduce that pressure. I have also developed a way of sleeping on the sensor arm with the hand of the other arm under the sensor arm just above the elbow which lifts the sensor up off the mattress a bit. I have gradually made this sleeping position a habit and it is surprisingly comfortable, kind of like giving yourself a hug with the Libre arm uppermost. I believe @Inka has independently also developed a similar posture to prevent compression lows and also finds it works. If you have the sensor too much to the inside it will likely be compressed by your ribs so finding a good spot is important.

As regards having loose skin I apply my sensor with my hand on my shoulder which tends to tighten up loose skin. I think this is important for the insertion process as much as how the sensor works afterwards. Taut skin will allow the needle carrying the filament to go through it more cleanly and easily as well as meaning that the adhesive will be attaching to smooth unwrinkled skin which will therefore allow better adhesion. I stand with the hand of the arm that the senor is going to be applied to on my opposite shoulder and looking in the mirror, I reach underneath with the applicator and apply it where I know it needs to be. I also hold it for a count of 100 before I wriggle the applicator free as that gives the adhesive a bit of time to form a bond with my skin and the applicator rarely comes away cleanly so giving it that bit of time and then gently wriggling it until it comes away, helps prevent lifting the sensor and disturbing or kinking the filament which can lead to sensor failure.

Thank you - this is all very helpful. I'll try some of these ideas

 

[Chris27]

I was recently advised to make sure I had sufficient fat for the filament to go into.
In my case, my arm is pretty lean in places and definitely more muscle than fat. As a result, I have changed my sensor placement and the accuracy has significantly improved.
However, I do not know how this "rule" applies when you have loose skin. It is possible that the sensor is not going into fat?

Thanks - this could be a factor.

 

[Mickeyminime]

I've noticed that the sensors don't seem reliable or accurate at all.

The laying down on the bed, even on my sides seems to make the levels drop and it can be quite annoying, even worrying at times if the prick machine doesn't work.

Then i've got this annoying worry when my levels drop so fast that i eat and it must take ages to go back up. If the prick works and the levels go up, it's not so bad, but if it doesn't work and the reading on the sensor keep going down regardless if i've eaten, i end up eating more. It happened the other night, i was sitting down and my levels started to drop very fast despite already eating a while ago. I tested myself but kept getting different errors so i ate again as a precaughtion. But despite eating, the levels continued to drop. I'm not sure if the graph changed over night, but the next day my levels where over 27 which is the first time it's been that high for more than a year.

 

[CathyFP]

All the above has been a bit helpful with my problem of the sensor reporting that I am low when I am not - but I’m still pretty worried how to manage this.

 

[Chris27]

Yes - join the club! I'm beginning to realise that the Libre technology is more approximate than I had thought. I am now doing regular prick tests to track the margin of error with my current sensor. Each reading is 1.5 to 1.8 mmols above the result of the prick test - ie not quite enough for me to claim a replacement. But it's the low readings (the previous sensor) which cause more disruption, for example when I am woken in the night by false alarms.

 

[Tdm]

All the above has been a bit helpful with my problem of the sensor reporting that I am low when I am not - but I’m still pretty worried how to manage this.

I was in the same situation...if the above ideas don't help, you may want to try dexcom cgm...i moved over and found they didn't wake me with false lows (i has 10 one night).
I still get compession lows with dexcom though.
A switch to dexcom ONE should be easy - you have an entitlement...i managed to get funding for g6 but i think i was lucky there...is a good sensor though

 

[helli]

Yes - join the club! I'm beginning to realise that the Libre technology is more approximate than I had thought. I am now doing regular prick tests to track the margin of error with my current sensor. Each reading is 1.5 to 1.8 mmols above the result of the prick test - ie not quite enough for me to claim a replacement. But it's the low readings (the previous sensor) which cause more disruption, for example when I am woken in the night by false alarms.

The degree of accuracy is not measure if mmol/l but in % so it will depend how high your BG is.
And, the "approved accuracy" is the same for finger pricks and CGMs - within 15% of your "real" reading.
If, for example your "real" BG was 6.0 - the reported reading could be anything between 5.1 and 6.9. So it is surprising if the difference is within 1 mmol/l.
And, if your "real" BG is in double figures the absolute difference can be quite a bit higher: 10.0 could be reported between 8.5 and 11.5.