Libre goes lower & lower - nickel allergy??

[Eddy Edson]

Consistently, Libre sensors start by working really well (vs fingerprick & common sense) for me, but then start to read lower and lower, particularly at low BG levels.

After a week, something like the attached pic - say around 0.7 lower than fingerprick and my "normal" levels on waking. Then often progressively sillier after that, for the rest of the sensor's life.



Do other people have the same experience? It's like the connection into the interstitial fluid degrades for some reason over time. I don't know why that would happen consistently, but one thought I had: maybe it has something to do with my nickel allergy?

This isn't very severe these days - used to be quite virulent, now just an occasional minor annoyance - but maybe there's still some reaction which degrades the connection somehow or other?

I don't find anything to support this on the Interweb but wondered if anybody else has seen anything along these lines in their travels.

 

[Ljc]

Mine often end up 2.0 ish below a fingerpick at around 10 days even when they start off pretty good . I think it’s to do with being factory calibrated rather than a daily calibration . Personally I don’t mind my sensors being no more than 2.0 out so long as they are consistent about being above or below, I have had one that wasn’t.

I am no medic but I suppose it’s possible that inflammation can affect the results .

 

[everydayupsanddowns]

I’ve not had that, or heard of that I’m afraid Eddy.

I’ve only ever had a handful of sensors that were consistently dodgy. 2 or 3 just never recovered and were replaced, but one or two started off a bit flaky (as the first 24 hours often did with the initial algorithm) but then carried in being quite a bit out for 4-5 days before finally settling and being fine.

I guess there’s a lot going on behind the scenes... the initial ‘trauma’ of the insertion, and then what each individual body does or doesn’t decide to to about the foreign object. Plus each insertion will be going somewhere slightly different, of course.

 

[mikeyB]

If you can find nickel in a Libre sensor filament, which I think is probably silicon, your surmise could fly. But there isn’t any. Nor is there any metal. So the theory is unlikely, to say the least.

It’s interesting that US sensors quit after ten days, which is the limit you are reaching, Eddy, so we may be discussing different things. Or the same things. I doubt Abbott could be bothered to make two different types for different markets - maybe in the more litigious US they stick to Ten days because they can’t be totally accurate for the last four. Who knows?

 

[Eddy Edson]

If you can find nickel in a Libre sensor filament, which I think is probably silicon, your surmise could fly. But there isn’t any. Nor is there any metal. So the theory is unlikely, to say the least.

It’s interesting that US sensors quit after ten days, which is the limit you are reaching, Eddy, so we may be discussing different things. Or the same things. I doubt Abbott could be bothered to make two different types for different markets - maybe in the more litigious US they stick to Ten days because they can’t be totally accurate for the last four. Who knows?

Yeah, I was thinking that if there atually was nickel there it would have been picked up by allergy sufferers somewhere on the Intertubes.

 

[trophywench]

Plus the fact that if you were displaying allergy - usually that would cause the BG to rise - cos it's inflammation, isn't it?

 

[Eddy Edson]

Plus the fact that if you were displaying allergy - usually that would cause the BG to rise - cos it's inflammation, isn't it?

Probably. I was thinking of some micro effect just affecting the contact points. Or something - dunno!

Actually, I don't think dermatologists have much of a clue either. The job seems to consist lagrely of saying, "Yes, you have an allergy and I can't do anything about it. That's $70 please. Help yourself to a mint".

I managed to largely cure mine by focusing on becoming older.

 

[Kaylz]

It’s interesting that US sensors quit after ten days

not all of them do though, the US has a 10 day system and a 14 day system

 

[Eddy Edson]

So just for fun I'm keeping this sensor going for the full 14 days.

A few days after my last post, it looks like this:



I am the anti-diabetic! My anti-liver produces blood-vinegar!

Versus fingerprick the decline has accelerated, from about 0.6 a few days ago to about 2.0 now. It's like the last three sensors, which must all have been from different batches. Why am I special??

Because the degree to which the thing reads low is accelerating, trying to calibrate reasonably well would require too many fingerpricks to make much sense.

Oh well. Maybe Libre v2.0 will work better.

The reason why I'm wearing a sensor now, apart from being a dork, was to check things in the lead up to my next HbA1c in a couple of weeks. Last time I got a result of 4.6% / 27 which I'm pretty sure didn't correspond very well to my actual BG levels. Hopefully using a Libre would provide some insight for this time, if my results still looked odd. Unfortunately, that plan hasn't worked out very well - unless my HbA1c comes in at 4.1% / 21, which is what the Libre is telling me 🙂

 

[SB2015]

Like others I have differences between my BG and the Libre.

Usually I can make a good guess at my BG from the Libre, using a combination of the reading, the arrow and the time lag and a bit of brain work. However if I am low the Libre tends to read even lower, if I am high it reads even higher.

As @mikeyB says the filament is silicon so no metal there, but there are times when I get a reaction in the final few days. This does not always impact on accuracy.

I still don’t use the Libre to decide on insulin doses, mainly because I have to do a fingerprick in my BG meter as it ‘talks’ to my pump. But I am thinking of going for a pump that would enable me to do this next time.

Not much help to you I know, but as you say you are just special.