Who signs off a Libre?

[Proud to be erratic]

I'm finding Dexcom a lot better than Libre, for what it's worth @dannybgoode. But be cautious about the interpretation of "better", or "reliable".

During 2021, I was getting over 50% failures from Libre and I initially assumed that was poor quality control by Abbott; after 12 months of this unsatisfactory situation I concluded that the problem was me - in that my body was incompatible with Libre 2. So many other users were happy with their Libres. I should add that Libre, even with such poor reliability for me, meant CGM was still a wonderful improvement from only finger pricking. This was a revelation! I learnt to tolerate the stress of unexpected sensor changes more frequently than "defined" and made the best that was possible out of differentials between actual and CGM ranging from irrelevant to up to 5 mmol/L - sometimes above, sometimes below, on the same sensor. (Pretty confusing to interpret at a glance)

Fortuitously, the NICE Guidance changed in mid '22, recognising that a single CGM provider was unreasonable and opening the NHS procurement to 4 providers in the lower cost group. I got myself switched to the long-standing original Dexcom One, which was definitely an improvement for me than Libre 2. But not brilliant. I self-funded the Dexcom G7 to see if there even was something that would work well on me; I then got a second revelation with a series of G7 sensors that worked continuously, with high levels of accuracy and provided a significant reduction from the stress of living with BG management. (My G7 is now provided by my Hospital).

"Reliable" is subjective from person to person and "better" is even more subjective. With brilliant reliability and accuracy of G7 for me, I still miss the Libre app, with its comprehensive logbook and easy to scrutinise statistics; I find (with only a mobile phone) Dexcom's web based Clarity less satisfactory than the Libre app. However the Dexcom G7 app allows me to see my graphs in portrait AND landscape view; suddenly all those peaks and troughs are really not "spikes", just a record of everyday undulating changes.

What works best for you is the all-important factor! But do try both Libre 2 and the new Dexcom One+. Each is equal cost to the NHS and neither your GP nor Hospital can, nor should, resist you from experimenting to find the best overall fit for you.

 

[Eternal422]

Following on from @Proud to be erratic, it does seem that some people get on better with Libre, some with Dexcom. I haven’t tried Dexcom as for me the Libre seems to be fairly accurate and works well. There is a failure rate with them though - I’m on sensor 72 since starting and have had 12 failures, so a 17% failure rate. Abbott have replaced every failed one free of charge and the information you get from them is amazing, well worthwhile.

 

[SimonP]

During 2021, I was getting over 50% failures from Libre and I initially assumed that was poor quality control by Abbott; after 12 months of this unsatisfactory situation I concluded that the problem was me - in that my body was incompatible with Libre 2. So many other users were happy with their Libres.

What was your failure mode? I also have troubles and am logging my sensors (in my sig) to try to get more than a gut feel for what is going wrong. I also find it strange that others have no problems yet I have both calibration and comms issues.

Regarding criteria for a sensor, interestingly for T1's in the very early days one of the criteria was that you had good control, rather than poor, in order to qualify, which I always thought was probably the wrong way around.

 

[dannybgoode]

No idea what the failure mode is - just wouldn't connect. May have been something I did wrong, knows. Anyway, Abbott are sending a new one out so that's good.

Have ordered a Dexcom also and will see which I prefer. I guess like any tech they go wrong from time to time, not a biggie for me.

Then will have the conversation with the GP/DS consultant and see what they say. I think with the exercise in particular it will be very useful and particularly when trail running etc gives an element of safety I would not otherwise have so will make my case.

So far everyone has been fine with my requests so hopefully this will continue 🙂

 

[Satan’s little helper]

To answer the initial question. In my case, it was the specialist at my diabetic clinic who instructed my GP to prescribe. My DSN at the time was disinterested. DSNs in my experience, still are. I’ve never known one to be engaged with LibreLinkUp. (It’s like they see the tech & move to their “safe space” of BP testing & foot tickles.)

 

[rebrascora]

@dannybgoode The sensors are started with NFC. Can you be sure that the NFC on your phone is functioning and unobstructed? Bank cards in your phone case can obscure it.
You do have to locate it quite precisely with a phone whereas with the reader, I can just pass it over my arm and it captures it easily. Not sure which phone you have or where the NFC is located on it. Some have it on the back instead of the front I think.

I am pretty sure many of the problems with failures of Libre are down to different phones and/or the LibreLink app or phone operating system updates. I think I have only had one sensor in the last year which was faulty and it finished a couple of days early, so on day 12 which they still replaced. When I first started using them, I lost one or two which I caught on clothing or door frames or loosened in the shower because I forgot which arm it was on when I was having a good scrub. Once I developed a good skin prep and application technique and bought an arm strap to give it extra support for the first few days, then I got great reliability.

 

[Satan’s little helper]

@dannybgoode The sensors are started with NFC. Can you be sure that the NFC on your phone is functioning and unobstructed? Bank cards in your phone case can obscure it.
You do have to locate it quite precisely with a phone whereas with the reader, I can just pass it over my arm and it captures it easily. Not sure which phone you have or where the NFC is located on it. Some have it on the back instead of the front I think.

I am pretty sure many of the problems with failures of Libre are down to different phones and/or the LibreLink app or phone operating system updates. I think I have only had one sensor in the last year which was faulty and it finished a couple of days early, so on day 12 which they still replaced. When I first started using them, I lost one or two which I caught on clothing or door frames or loosened in the shower because I forgot which arm it was on when I was having a good scrub. Once I developed a good skin prep and application technique and bought an arm strap to give it extra support for the first few days, then I got great reliability.

I’ve had (to date.) 3 phones using Libre. Without exception. The NFC on the back of the phone needs touching directly to the sensor to start it. Or scan it. Probably a security feature regarding the “tap & pay?”

 

[Lucyr]

No idea what the failure mode is - just wouldn't connect. May have been something I did wrong, knows.

Do you use your phone to make contactless payments and does that work ok?

 

[dannybgoode]

The sensors are started with NFC. Can you be sure that the NFC on your phone is functioning and unobstructed?

My phone scanned the sensor just fine. Waited the hour and it just have signal lost. Tried a manual scan and it just said sensor failed.

I love tech, I'm very comfortable using pretty much anything so reasonably confident it was nothing I did.

They're sending another sensor so will see where I get to. Got the Dexcom on order too and will compare.

My DSN at the time was disinterested.

The DSNs at the Northern General are all over anything that will help patients so no concern as such that I'll hit barriers. Just wanted to take the best route in for it 🙂

 

[everydayupsanddowns]

Fingers crossed for you @dannybgoode

Hopefully your need for MDI, your sensitivity to insulin, and the slightly ‘borderline’ nature of your diagnosis will weigh in your favour.

 

[mashedupmatt]

My phone scanned the sensor just fine. Waited the hour and it just have signal lost. Tried a manual scan and it just said sensor failed.

I love tech, I'm very comfortable using pretty much anything so reasonably confident it was nothing I did.

They're sending another sensor so will see where I get to. Got the Dexcom on order too and will compare.

The DSNs at the Northern General are all over anything that will help patients so no concern as such that I'll hit barriers. Just wanted to take the best route in for it 🙂

Have had that a couple of times recently - you should get the replacement early next week and strangely enough never had a replacement one fail - maybe a dodgy batch - I use the "Not just a Patch" ink splot patches to keep mine in place and they work very well

 

[dannybgoode]

Fingers crossed for you @dannybgoode

Hopefully your need for MDI, your sensitivity to insulin, and the slightly ‘borderline’ nature of your diagnosis will weigh in your favour.

Apparently the DS consultant I'm seeing is very nice and the GPs are usually pretty good as well so fingers crossed.

Will update as and when I get some sensors going 🙂

 

[Satan’s little helper]

The DSNs at the Northern General are all over anything that will help patients so no concern as such that I'll hit barriers. Just wanted to take the best route in for it 🙂

It probably depends on the area with DSNs. I’ve had to paddle my own canoe in that respect for years & just leave them to draw blood. Let us know how you get on?

 

[dannybgoode]

It probably depends on the area with DSNs. I’ve had to paddle my own canoe in that respect for years & just leave them to draw blood. Let us know how you get on?

Definitely. I seem to have landed in my feet with the Sheffield team for sure. Will see how it pans out over the next few weeks...

 

[SimonP]

I am pretty sure many of the problems with failures of Libre are down to different phones and/or the LibreLink app or phone operating system updates. I think I have only had one sensor in the last year which was faulty and it finished a couple of days early, so on day 12 which they still replaced.

It's very strange how some people have no problems, yet I quite often have complete Bluetooth failures (which is one of the failure modes I see, the other is calibration issues).

It's not my phone as far as I can tell. Running a BLE scanner app shows other devices quite happily transmitting, but no sign of the libre2 transmitting its signal every minute or so. Sometimes I have drop-outs which only last from a few minutes to a couple of hours (and Juggluco notes a connection failure and keeps listening and reconnects when the signal comes back), though once I see these happening it's very likely that the sensor won't last the distance and will eventually fail permanently.

I suppose it's theoretically possible that there's some sort of partial failure of the Bluetooth stack, though switching Bluetooth on and off, and rebooting, have no effect, but starting a new sensor does work and the phone can see it quite happily, which leads me to believe that it's the sensor that has failed rather than the phone.

I do use the reader (v2) to start the sensors and thereafter I use Juggluco to listen for the broadcasts (I must check that this is actually totally passive, as if not that is a potential failure mode, though I've not seen vast swathes of users reporting similar problems. I wonder if the librelink app is able to tell the sensor to restart its Bluetooth subsystem if there's an error detected, which I'm therefore missing with my setup - presumably other users, even if they use Juggluco, have to upload their data somehow, which might be by starting LibreLink every now and again.

I'm clutching at straws re an explanation and have also dragged the thread rather off-topic, sorry!

 

[Satan’s little helper]

Definitely. I seem to have landed in my feet with the Sheffield team for sure. Will see how it pans out over the next few weeks...

You have my sincere best wishes. I once had the pleasure of chatting in a casual informal setting with a DSN who practises outside my area. She happened to clock my sensor set up. & knew her stuff. They are “out there.” Like playing “Pokémon go” I’ve not seen one in 30 years.

 

[rebrascora]

@SimonP When you get those BT fails have you tried scanning with the reader to see if the sensor is still working? This may be why I am not having problems in that I am not using the BT, just the NFC.

 

[SimonP]

@SimonP When you get those BT fails have you tried scanning with the reader to see if the sensor is still working? This may be why I am not having problems in that I am not using the BT, just the NFC.

NFC always works, so the actual BG sensing part is working, it's the Bluetooth part which fails. I think I've only ever had a single sensor which stopped working (reporting BG) and told me to replace it - more usually I end up with >4mmol/l offsets or BLE comms failures, which negate quite a lot of the point of having the sensor (overnight low protection.)

It's not a particularly new thing, this has always happened, though when the libre2 first came in I had a long run without any BLE failures (so long that I stashed my miaomiao2 somewhere and still can't work out where I put it to keep it safe - unfortunately they don't seem to be very easy to come by these days/those that are left are very expensive otherwise I'd buy another and my arms wouldn't suffer quite so much!)

Interestingly looking at teardowns of the sensors the Bluetooth and NFC functionality are provided by the same dedicated chipset, so it's not full a chipset hardware failure, more likely an antenna or firmware failure (hence my comment about resets triggered by using the Librelink app.)

I do find it somewhat hard to believe that it's just me who is particularly prone to damaging the Bluetooth antenna, but there's still the possibility that my phone's NFC accidentally cooks the Bluetooth antenna when scanning (which is why I've now stopped scanning when the sensors go offline in order to see if this makes any difference.)

I've read that some phones can damage NFC devices, though it's mostly heresay, so hard to know how much to trust this, but again trying to work out what might be the root cause.

So the plan of attack, fwiw: 1. stop NFC scanning, see how I get on; 2.Start and occasionally scan using the librelink app; 3. Get a new phone (one on the "accredited" list), though I don't need a new one and I'll then need to carry two around with me while testing if I source an old one just for testing, which will be a PITA, but c'est la vie.

I also need to move the sensor onto my tummy to see if that works better from a calibration point of view, though I'm still trying to work out where exactly would work best (seeing that the Dexcom guidance says at least 8cm iirc away from insulin injection sites).

 

[Ttelmah]

You can get a 'sensor error', if the reading changes sharply. It recovers quite quickly on the more modern sensors.
I've been using the Libre3 for 7 months and have had just one faulty sensor.
Key though is to put them well 'under' the arm, not to the rear.

 

[SimonP]

I've been using the Libre3 for 7 months and have had just one faulty sensor.
Key though is to put them well 'under' the arm, not to the rear.

I'm guessing this doesn't affect the occurrence of Bluetooth failures, but might affect calibration issues? Or is there a different sensor fault you experience?