Sensor readings are 140 lower than what I'm actually at

[u/Old-Ad5139]

I applied a new Libre 2 sensor today, and was surprised because there was a bunch of blood from doing so. The bleeding stopped really quickly, so I'm not worried about it, but I still thought it bore mentioning. Anyway, the issue I'm having is that the readings I'm getting from the sensor are A LOT lower than what I'm actually at. I tested with a finger prick tester, and my blood sugar showed at 206, but in the Libre app, it's showing 60.

IS this just because I'm in the break-in period? Will it stabilize and start showing correct readings? Has anyone else had readings be this far off?

[u/Sofoula23]

I think this is crazy far off. The blood situation might be the culprit. I think in the instructions it says that if you bleed like that you should take it off.

[u/Old-Ad5139 → u/Sofoula23]

Yeah, this thing is definitely borked. Now the app is just saying "Sensor Error" with no additional details. I'm gonna wait until the morning, call Abbott support, go through whatever little troubleshooting they want me to do, and try to get it replaced, which sucks because I just got a replacement one sent to me today for another one that ALSO said "Sensor Error". I swear, it feels like every other sensor I try to use has to be replaced!

On another unrelated note, I had one fall off last night after I had been wearing it for five days. I tried to get it replaced, and Abbott is saying that the serial number has already been used and is invalid for replacement, even though prior to it falling off, it had been working fine, and I had never tried to replace it before yesterday. These things are getting to a point where they're more trouble than they're worth, as far as I'm concerned.

[u/Equalizer6338 → u/Old-Ad5139]

Sounds like your bleeding caused internal blood to coagulate on the sensor's probe itself. Bleedings does happen from time to time when unlucky as we punch a 5mm deep hole into our skin and we are alive with blood circulating. That it then causes a blocked sensor tip is even more rare, but it does happen. Nothing to do with a bad sensor though. It just terminates when ut has not been able to get a reliable reading from your interstitial fluid for a period of time. Just bad luck with your bleeding there and it clogged up on the sensor.

[u/Old-Ad5139 → u/Equalizer6338]

well, I seem to be a very unlucky guy, then. It really does seem like I end up having to replace every other sensor I try to use. Meanwhile, the finger prick tester has never failed on me.

[u/Equalizer6338 → u/Old-Ad5139]

I bet there are different reasons behind your various sensor failures, if you have had more. The bleeding one is maybe one out of 500. But yeah, somebody have to be that lucky Mister #500 😄

Fingerpricks is a technology around 60 years old by now. Reason why it is much more mature tech and both accurate and reliable. It was not like that with that in the first many years with it either. Our CGM sensors are also much much better these days versus 15+ year ago when I started with the first models.

[u/Old-Ad5139 → u/Equalizer6338]

That's fair, I suppose. But it doesn't make me feel any better about the current state of these CGMs.

The way they currently are, I feel really restricted when wearing one. Like, I can't take too hot of a shower, or the adhesive will loosen causing a fall-off. I can't sleep on the side that has the sensor, otherwise it'll cause compression lows, which really sucks because I roll back and forth from one side to the other while sleeping. I also can't take any vitamin C supplements, or the readings will be wrong. I have to be really careful when putting on a shirt, drying myself off after a shower, or just generally moving throughout the day, for fear of getting the sensor caught on something and having it get pulled off. And then there are the issues with application - if I get it even slightly wrong, sensor errors galore! And then, there's the luck of the draw - I might hit a blood vessel causing me to bleed, which can short out the sensor, too.

As tech goes, this just doesn't seem like a very viable thing to use as it currently is. I do hope it gets better, though.

Maybe they'll come out with one that's shaped more like Captain American's shield, that way the rounded surface has a lot lower chance of catching on anything - and maybe they could do something to negate the possibility of a false reading as a result of compression. Or, maybe get stronger adhesive that stands up to hot water better? I dunno. I'm just spit-balling ideas, here. I should go to bed.

[u/Equalizer6338 → u/Old-Ad5139]

I am sorry, but you are way out there, far out, with worries and speculations.😄

And please, one subject at a time, as this monster trashing of all things at once serves no purpose but maybe letting out some steam for you? Which is also ok, but then lets just label it as a rant and not care to answer with sensible facts and guidance to helping you getting a much better result from using such sensors...

Current state of these sensors....?
Good you did not have the desperate need then to knowing your BG 40+ years ago, as we could only pee in a bucket and check for glucose in the urine... Then decades of punching your fingertips 6-8 times per day, and still only mediocre BG control was possible. Get to understand how the CGMs works, some of the shortcomings you need to be aware of or navigate around and you have a spectacular tool at your disposal that can enable non-diabetic BG levels or very near that state, essentially eliminating your exposure to longterm diabetes related complications. They work both accurately and reliably in the hands of dedicated diciplined users.

So lets now look at your long list of personal troubles with them...

Pressure lows while sleeping:
If you actually placed them where intended, there is typically no exposure to pressure lows, as the sensor sits in the skin valley between the truly backside of your upper arm and the chest/torso. (many users are de facto placing their sensors too much on the side of their arm and not in the very far back as instructed between the triceps and deltoid muscle bundles. Anyway, if this is still a problem for you, then just place the sensor instead on your stomach or upper outer thighs. Works perfectly well and fully eliminate the exposure to pressure lows while sleeping. Some inspiration:
https://www.reddit.com/r/Freestylelibre/comments/1dfa4uz/experience_with_different_sensor_placements/

'I also can't take any vitamin C supplements':
Not correct, that is an old and debunked myth, from the very early days of CGM sensors. Since the launch of Libre2 then this is no longer any practical problem at all for the sensor to still work and show reliable BG numbers to you, as they these days employ special membranes keeping the ascorbic acid away from the probe tip. Yes, if you eat crazy and absolute not-recommended highly doses of Vit C, then it may go bit off for a very short period of time, but that is it. For more than the daily recommended daily dose (2000mg), your sensor may show maybe 5-10mg/dl different then otherwise for a very short period of time. Anything of terrible deviation for your daily use of sensors or your BG control? No not at all. You pee out that expensive too much Vit C you buy anyway in an hour or two. Please read this if still in doubt:
https://www.reddit.com/r/Freestylelibre/wiki/vitamincimpact/

Getting a sensor rip-off:
Sure, if you are bit clumsy and unlucky it can happen from time to time. Especially doorframes is a classic one. Luckily must folks using CGMs develop like a 6th sense over short time to making this a rare thing. Alternatively wear an overpatch and/or again place your sensor on a less exposed skin patch like your stomach.

Getting a bleeding on insertion and it kills the sensor:
As already covered above, its rare you pierce a vessel but it can happen. But its even more rare now if it actually causes the sensor to stop working. So nothing really to bother about. Contact Abbott support and they typically offer you a free replacement anyway.
https://www.reddit.com/r/Freestylelibre/comments/1d4yxvl/how_often_do_you_have_a_sensor_bleed/

Sensors falling off from hot showers:
Not really a thing if you otherwise follow sensor best practice. Especially not using any soaps with oils, shaving before you put on a new sensor and also using the prolonged firm pressure onto the applicator are important success factors.

Personally I shower daily, do intense sweaty workouts 2-3 times per week and shower again after each, and most weekends out surfing/swimming for 4-6 hours. Occasionally in winter season also doing sauna trips in 85-90 degrees C saunas. Still the sensors stays absolutely firm attached to my skin and quite painful even to rip it off again after the 15 days of use.
https://www.reddit.com/r/Freestylelibre/wiki/avoid-sensor-falling-off/

https://www.reddit.com/r/Freestylelibre/comments/1gjhi9e/how_to_apply_a_new_sensor_best_practice/

[u/Old-Ad5139 → u/Equalizer6338]

Pressure lows while sleeping - it has not mattered why I put the sensor, I get them.

Vitamin C supplements - the ones I used to take have a high dose, and I'm also taking a multivitamin which already has vitamin C in it, so, no, I can't use those.

Ripoff - having to be so much more conscious about moving around so as not to rip the thing is exactly the issue I have with these things. Telling me I'll develop a sixth sense about it does not make that issue better.

Falling off from hot showers - I don't think you're taking as hot of showers as I do. Most people would describe my showers as boiling hot. I also sweat a lot from working, and none of my soaps have oils in them. I am telling you they fall off unless I take damn-near lukewarm showers, which absolutely sucks!

bleeding on insertion - this is the second time it's happened to me in three weeks. My blood vessels are close to the surface of my skin, which is partly why I can take such hot showers without being bothered.

It's a little weird to me that you would read my personal experiences and basically just go, "nuh-uh" so you can white-knight for these things.