Libre sensor issue…false hypo before error?

[merrymunky]

Hi all,

I just wondered if anyone else has experienced similar while using a libre 2 sensor.

The low glucose alarm went off at about 12.55am today. Did a scan and my reading was 3.8. Drank some lucozade and went to the toilet. It took an hour for the sensor to fix itself and start scanning again. In the meantime I did a finger prick about 5 minutes after the initial alarm and my level was 8.8. Seems a very quick rise for 1 drink of lucozade.

I’m wondering if the sensor can give a false hypo reading if it is losing signal?

I had a similar situation with the ge same sensor yesterday morning. It said I had a hypo, so I corrected it but a few minutes later the data had changed and there was no record of it on the graph or logbook.

 

[helli]

If you woke up to the alarm, could it be a compression low? These usually happen at night when we live on the sensor and the pressure causes it to falsely report a low.
The advice is to always finger prick test before correcting a high or low (unless you feel hypo) as CGMs are less accurate when outside normal range.

Did you have a loss of signal or a "scan again in 10 minutes". If the latter, this happens if the sensor is struggling with your numbers which maybe because it is changing quickly, especially if you are treating a hypo so it is rising fast.

If you are having alarms at night, they sound more like compression lows than loss of signal problems.

 

[littlevoice359]

I’ve also experienced instances, during hot weather mainly, of Libre showing a false downward trend due to the fact that I had become a little dehydrated.

When wearing Libre (or Dexcom or any CGM sensor that works by measuring interstitial fluid), it is important to drink enough liquids to stay hydrated.

I also learned, unfortunately the hard way, to always check with a finger prick test before correcting for a low or high. Otherwise you can get nasty surprises.

 

[Kaylz]

Always check via finger prick, Abbott do recommend this in the small print too, the Libre can be highly dangerous to rely on as someone found out when they ended up in hospital in DKA when their Libre had been showing in range so they hadn't checked

 

[merrymunky]

If you woke up to the alarm, could it be a compression low? These usually happen at night when we live on the sensor and the pressure causes it to falsely report a low.
The advice is to always finger prick test before correcting a high or low (unless you feel hypo) as CGMs are less accurate when outside normal range.

Did you have a loss of signal or a "scan again in 10 minutes". If the latter, this happens if the sensor is struggling with your numbers which maybe because it is changing quickly, especially if you are treating a hypo so it is rising fast.

If you are having alarms at night, they sound more like compression lows than loss of signal problems.

I always make sure not to sleep on the side with the sensor. I wasn’t lying on it at the time.

I did get that message for a solid hour yes. I had a hypo on Friday that took over an hour to correct. Seems weird that this would rise in just 5 minutes.

 

[merrymunky]

I’ve also experienced instances, during hot weather mainly, of Libre showing a false downward trend due to the fact that I had become a little dehydrated.

When wearing Libre (or Dexcom or any CGM sensor that works by measuring interstitial fluid), it is important to drink enough liquids to stay hydrated.

I also learned, unfortunately the hard way, to always check with a finger prick test before correcting for a low or high. Otherwise you can get nasty surprises.

Good advice. I think I will make sure I finger prick test and check again before diving into a treatment next time.

 

[merrymunky]

That

Always check via finger prick, Abbott do recommend this in the small print too, the Libre can be highly dangerous to rely on as someone found out when they ended up in hospital in DKA when their Libre had been showing in range so they hadn't checked

That’s quite alarming isn’t it? Surely they should be developing a system that doesn’t have such a wide error margin. Especially given how expensive the libre is.

 

[helli]

That

That’s quite alarming isn’t it? Surely they should be developing a system that doesn’t have such a wide error margin. Especially given how expensive the libre is.

No I don’t think so. The cost of Libre is irrelevant. The guidelines for using it should be clear. I know I have been told multiple times to test before treating.
The technology is great but only if you understand the limitations and know how to use it. This is not a Libre limitation- this is a limitation of the science that is used with reading interstitial fluid.
Libre is the cheapest CGM and the advice is the same for all.

 

[merrymunky]

I’ve had the worst night with this sensor. Literally went off every hour telling me I was in hypo but every time I’ve been 5 or over on a finger prick. It has to be a faulty one surely. I’m not lying on it. I’m suffering from really horrid shoulder and neck pain on my left side but won’t turn over to lay on my right because of the sensor.

My last two never did this.

I’ve barely slept. Oh and I ended up on the sofa in the playroom because a spider decided to run down my arm and into the bed too a few hours ago. I could cry. I won’t go back into the bed till I know it’s gone but it ran behind the mattress/pillows and no idea where it went. Gah!!

 

[littlevoice359]

Unfortunately this does happen occasionally where a sensor reads sufficiently low or high as to cause false alerts. I had such a sensor at the end of June that was really annoying.

Some members choose to replace such sensors. That’s fine if you have a spare to hand. I choose to work around the problem using a third-party Android application (xDrip - works by reading an adapter that sits on top of the Libre) that lets me calibrate each Libre sensor to finger-prick test results.

Personally, I find Abbott’s claim that their sensor does not need to be calibrated against finger tests to be nonsense, but I fully accept that mine is not the only view on the subject.

 

[Purls of Wisdom]

I always make sure not to sleep on the side with the sensor. I wasn’t lying on it at the time.

I did get that message for a solid hour yes. I had a hypo on Friday that took over an hour to correct. Seems weird that this would rise in just 5 minutes.

In my limited knowledge the advice is if a hypo is not corrected after 3 treatments in 30 mins; call 999.

 

[everydayupsanddowns]

I’ve definitely had that when a sensor died, but immediately before it gave the impression that my BGs had dropped off a cliff.

And I have had Libre sensors which consistently read differently to fingersticks.

Call Abbott, and they can talk you through troubleshooting the sensor (all pretty obvious stuff), and will replace it if it’s not performing to their expectations.

Keeping well hydrated (especially in this warmer weather) really helps my sensors to function better.

 

[Proud to be erratic]

Bad luck, when a sensor plays up its a real nuisance

I’ve had the worst night with this sensor. Literally went off every hour telling me I was in hypo but every time I’ve been 5 or over on a finger prick. It has to be a faulty one surely.

Was there a broad consistency between your actual BG and the sensor reading? If so you could try setting the sensor alarm very low, knowing that it's is consistently low. Also, at post #3, there is a comment about making sure you are fully hydrated, since the interstitial fluid is easily affected by potential dehydration.

I’m not lying on it. I’m suffering from really horrid shoulder and neck pain on my left side but won’t turn over to lay on my right because of the sensor.

My last two never did this.

Early days. Contact Abbott, by phone or email and they are normally very good about replacing faulty sensors. My own reliability success is not good, over 50% replacements, but that doesn't seem to be a wider problem with Libre users. I persevere and work with faulty sensors because I consider the alternative, no CGM, to be a big backward step. But each time I have to change a sensor is a pain in the .....; I need at least 24 hrs for it to bed in and produce consistent readings so an early sensor change is a day of necessary, but not desired, finger pricking.

 

[Proud to be erratic]

In my limited knowledge the advice is if a hypo is not corrected after 3 treatments in 30 mins; call 999.

I'm not sure this is a good 'rule of thumb'. If it's a really deep hypo, then probably OK, but I think not for milder hypos.

Before I had Libre I spent the best part of a year with erratic BGs and lengthy periods in hypo-land, confirmed by finger pricking. Sometimes I'd get a fairly rapid response from my Jelly Babies, but sometime I'd spend well over an hour below 4 and with continuing modest hypo symptoms. For whatever reason my body was going its own way.

Gradually I realised that each hypo was a great nuisance, but wasn't going to kill me and I found I could resist the temptation to panic and over-react. This left me personally feeling better about my D management skills as well as helping me get off the roller coaster from hypo to hyper and back again. Interestingly, for me, the hardest part was resisting the urge to eat; my hypo symptoms include my body screaming at me "feed me".

 

[helli]

I'm not sure this is a good 'rule of thumb'. If it's a really deep hypo, then probably OK, but I think not for milder hypos.

I agree but I think it is another one of those "we are all different" examples.
To me the issue is how I am managing the hypo. An ambulance has only been called once for me in nearly 20 years and that was because I was unconscious. I have had other hypos that last over an hour to get above the 4 mark but as they were in the 3s, I just carried on treating them.

The other thing I would say is that given the advice is to treat, wait 15 minutes, test and treat again, 3 treatments would be 45 minutes, not 30. Otherwise, you are calling an ambulance before you have given the third treatment time to work.

If I was feeling particularly concerned, I may call 111 for advice but, if I was conscious, I would not call 999 for a hypo.

 

[merrymunky]

I'm not sure this is a good 'rule of thumb'. If it's a really deep hypo, then probably OK, but I think not for milder hypos.

Before I had Libre I spent the best part of a year with erratic BGs and lengthy periods in hypo-land, confirmed by finger pricking. Sometimes I'd get a fairly rapid response from my Jelly Babies, but sometime I'd spend well over an hour below 4 and with continuing modest hypo symptoms. For whatever reason my body was going its own way.

Gradually I realised that each hypo was a great nuisance, but wasn't going to kill me and I found I could resist the temptation to panic and over-react. This left me personally feeling better about my D management skills as well as helping me get off the roller coaster from hypo to hyper and back again. Interestingly, for me, the hardest part was resisting the urge to eat; my hypo symptoms include my body screaming at me "feed me".

Oh this hypo was probably totally my own fault. We went out for tea and I took a big old dose of insulin ( although I did calculate from the nutritional advice) but because it was a particularly naughty tea I think the insulin made me go low before it really had a chance to be absorbed with the food if you get me! I took enough to cover my meal and dessert and spent a few minutes before my dessert came eating hypo treatment sweets and having to drink sugary pop so I was bloody stuffed before I even got to dessert!

 

[Proud to be erratic]

@merrymunky , my apology my response about the rule of thumb stands OK in itself, but I was really replying to a comment made by @purlsofwisdom in your posting and inferring calling 999 if one's response to a hypo didn't work after 30 minutes.

Oh this hypo was probably totally my own fault.

And that's OK, because just knowing what you did to probably cause the hypo is really useful in itself. We all learn from our experiences, far better than someone telling us.

We went out for tea and I took a big old dose of insulin ( although I did calculate from the nutritional advice) but because it was a particularly naughty tea I think the insulin made me go low before it really had a chance to be absorbed with the food if you get me! I took enough to cover my meal and dessert and spent a few minutes before my dessert came eating hypo treatment sweets and having to drink sugary pop so I was bloody stuffed before I even got to dessert!

This sort of resonates with what I said, in that when I have mild hypo symptoms, the urge to eat something can overtake sense. You'd already got some food on board and chances are that in 5 mins that would have digested enough for those carbs to catch up with the insulin. (Unless it was all cream and minimal scones! The fat content does slow down the digestion.) But in practice you probably would have been fine and the hypo would have dissipated on its own.

Another way to manage such a naughty tea, could be to split the bolus: take some of your calculated dose straightaway then some later - how much later depends on how the meal progresses; or not at all if you just don't have room for the dessert.

Anyway, as I remarked previously, it's early days. Lots to learn about yourself and managing your D.