Weird Libre 'problem'

A

AndyGlos

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Type 2
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I am not sure which Forum to put this on but I know some knowledgeable people might have come across this scenario.

Have been using the Libre 2 system with a hand held reader (I don't have a phone that does Apps). I had this problem a couple of weeks ago but needed to experiment to see if it recurred.

When I have the sensor on my left arm all is well and the readings are within a sensible range of a finger prick. Yesterday I changed back to my right arm and the readings are way out again. Last night I kept getting low sugar alarms which woke me up. A finger check told me I wasn't hypo. This morning the reader was 5.7 which I thought was good. But I thought I would double check and the finger prick was 9.5 both before food, scrambled egg this morning. Now at lunchtime the reader is 5.9 but finger prick is 8.7. I know they say allow about 10% between the 2 readings but not sure there should be a big difference between 2 arms with the same blood in them! I really don't want to have to do finger pricks for the next 2 weeks until I move the sensor back to my left arm.

Thanks for any comments which might explain this or if anyone has had the same problem. Oh and yes I know I am weird. Just ask my GP hehe.

Andy
 
The lows through the night are likely compression lows, where the Libre gives a false low reading due to lying on it in your sleep. Positioning it further towards the back of the arm should prevent this.
As regards the discrepancy today, some people experience what we call inserion trauma where the tissue that the filament is fired into reacts to the foreign body in it's midst and gives less accurate readings for the first 24-48 hours but generally settled down after this. As a result, some people apply their new sensor a day or two before the old one ends to allow it longer to bed in before they activate it and any reaction to subside. I generally find 12 hours in advance is fine for me.
I also only compare my Libre against a finger prick when my levels are ticking along nice and level for about half an hour mid range, so I waatch my Libre for a time when things are nice and stable in the 5-6s for half an hour and check it against a finger prick then. First thing on a morning before breakfast, my levels would be rising quite quickly due to my liver releasing glucose (Dawn Phenomenon/Foot on the Floor Syndrome), so I would not find that a reliable time to compare my Libre to a finger prick.
Hopefully your current sensor will settle down and you will find a better placement of the next sensor to avoid compression lows when you are sleeping. I sleep mostly on my back and find the back of my arm fine. It seems to be when is is on the side and all your weight is pressing it into the mattress when you lie on that side that it happens. If I sleep on that side I have also developed a sleeping position where I put my other hand just under my sensor arm above the elbow to lift the arm slightly off the mattress. This also helps create a gap under the sensor to stop it getting compressed. I have gradually learned to adopt this position as a habit so that when I roll over in my sleep, I naturally do it. It may sound a bit far fetched to imagine you can do this but we do have positional and spatial awareness when we are asleep which is why we don't roll out of bed or into our partner, so you can learn to do this too.
I think with the warmer weather people are tossing and turning more in their sleep so compression lows are more likely to happen at this time of year. Hopefully you will find a fix.

If your sensor remains more than 2mmols out from your finger prick tomorrow, you can ring Abbott customer services and they will usually replace it if you have 3 comparison finger pricks which show it is more than 2mmols out. There is also an online reporting option to do this although I haven't personally used that yet.
 
Do you sleep on your right side? If do the night time lows are probably compression lows. Basically it’s getting squashed and not able to function properly. I always put mine on my right arm as I sleep on my left one. I know some folks say you’ve to change arms but my DSN says it didn’t matter. So just put yours on your favourite arm no harm will be done. Obviously move it to another place each time. Sometimes the first day or two they can be a bit wafty see if it settles, if after 2/3 days it’s still reading 3 mmol over contact Abbott for a replacement. They’ll ask lots of questions and will need an example of when it’s been vastly different. Remember that it’s the patterns that count, back in the day we didn’t know what was going on between our mealtime finger pricks. Obviously if you’re an insulin user you always need to finger prick if you think you don’t feel they way the Libre is telling you for example if you’re low/high and you don’t feel that way. The Libre is a God send but it does give you info overload sometimes!

If you’re on Facebook there’s a UK Freestyle Libre group that can answer your questions.
 
Just beat me to it Barbara!
 
rebrascora said:
The lows through the night are likely compression lows, where the Libre gives a false low reading due to lying on it in your sleep. Positioning it further towards the back of the arm should prevent this.
As regards the discrepancy today, some people experience what we call inserion trauma where the tissue that the filament is fired into reacts to the foreign body in it's midst and gives less accurate readings for the first 24-48 hours but generally settled down after this. As a result, some people apply their new sensor a day or two before the old one ends to allow it longer to bed in before they activate it and any reaction to subside. I generally find 12 hours in advance is fine for me.
I also only compare my Libre against a finger prick when my levels are ticking along nice and level for about half an hour mid range, so I waatch my Libre for a time when things are nice and stable in the 5-6s for half an hour and check it against a finger prick then. First thing on a morning before breakfast, my levels would be rising quite quickly due to my liver releasing glucose (Dawn Phenomenon/Foot on the Floor Syndrome), so I would not find that a reliable time to compare my Libre to a finger prick.
Hopefully your current sensor will settle down and you will find a better placement of the next sensor to avoid compression lows when you are sleeping. I sleep mostly on my back and find the back of my arm fine. It seems to be when is is on the side and all your weight is pressing it into the mattress when you lie on that side that it happens. If I sleep on that side I have also developed a sleeping position where I put my other hand just under my sensor arm above the elbow to lift the arm slightly off the mattress. This also helps create a gap under the sensor to stop it getting compressed. I have gradually learned to adopt this position as a habit so that when I roll over in my sleep, I naturally do it. It may sound a bit far fetched to imagine you can do this but we do have positional and spatial awareness when we are asleep which is why we don't roll out of bed or into our partner, so you can learn to do this too.
I think with the warmer weather people are tossing and turning more in their sleep so compression lows are more likely to happen at this time of year. Hopefully you will find a fix.

If your sensor remains more than 2mmols out from your finger prick tomorrow, you can ring Abbott customer services and they will usually replace it if you have 3 comparison finger pricks which show it is more than 2mmols out. There is also an online reporting option to do this although I haven't personally used that yet.
Click to expand...
Hi Barbara
Thanks for your usual detailed reply. I had read about compressions lows before but I don't think that's true in this case. I sleep on my left side due to my CPAP machine and where it is on the floor and am one of those people that stays put when asleep (according to my late partner). I didn't have any problems when it was on the left arm and sleeping on it, just happens on the right. I do place them right on the back of my arm as the DN said that was best. But I hadn't thought about the trauma aspect. I will give it a couple of days again but last time it happened for the whole 2 weeks I had it on the right.
This evening a low glucose alarm went off before dinner and reading was 2.8! Finger prick was 9.4 The good thing is that both devices record everything so I can't be accused of faking it by my DN or Abbots.
I think I shall have to ask Abbots what they think could be causing it though. I'm on the point of just back to the old system and do 3 checks a day unless I feel wonky. Or maybe I have 2 blood systems ;-)
Regards
Andy
 
eggyg said:
Do you sleep on your right side? If do the night time lows are probably compression lows. Basically it’s getting squashed and not able to function properly. I always put mine on my right arm as I sleep on my left one. I know some folks say you’ve to change arms but my DSN says it didn’t matter. So just put yours on your favourite arm no harm will be done. Obviously move it to another place each time. Sometimes the first day or two they can be a bit wafty see if it settles, if after 2/3 days it’s still reading 3 mmol over contact Abbott for a replacement. They’ll ask lots of questions and will need an example of when it’s been vastly different. Remember that it’s the patterns that count, back in the day we didn’t know what was going on between our mealtime finger pricks. Obviously if you’re an insulin user you always need to finger prick if you think you don’t feel they way the Libre is telling you for example if you’re low/high and you don’t feel that way. The Libre is a God send but it does give you info overload sometimes!

If you’re on Facebook there’s a UK Freestyle Libre group that can answer your questions.
Click to expand...
Thanks Eggy
I sleep on my left as explained to Barbara.
Your comment on being told not to worry too much if it stays on one arm is good. The number of times I go to scan the wrong arm after a change bugs me. Seriously though if I know it's going to work properly all the time on the left then I can stick with that.
I am on insulin which is why I am double checking when I know I don't feel like I am having a hypo yet moaning Minnie is telling me I am low sugar. Equally when my vision goes blurred and the reader says normal, I get the old finger pricker out. I think I'm going back to the old ways. This technological malarkey is above my pay grade. Which is why tomorrow I am going shopping in a 120 year old car.

And sorry I don't do FB after a nasty experience.
 
When I recently had issues with my CGM, I was advised to check i had at least 5mm of fat where I inserted my sensor. Turned out the sensor was positioned in a very lean part of my arm.
Is it possible the position you use on your right arm does not have enough fat?

I do not know what you mean by the 10% difference between the readings
Both blood glucose meters and CGMs are required to be within 15% of the "true" reading. Therefore, of you are comparing two readings they could be more than 10% difference if one is reading close to 15% higher than true reading and the other reading close to 15% lower.
 
There has been some research done on the accuracy of readings between L and R arms. Seems that some people have a definite discrepancy.

www.ncbi.nlm.nih.gov

Differences in Glucose Readings Between Right Arm and Left Arm Using a Continuous Glucose Monitor

Continuous glucose monitoring (CGM) devices are used for evaluating real-time glucose levels to optimize diabetes management. There is limited information, however, on whether readings differ when a device is placed on the right versus the left arm. This ...
www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov

It’s a bit “medicalised” but you’ll get the gist
 
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