@Gork , according to my reader stats, I'm now on my 57th sensor, been using it for about 2 years now.
Sure, 4 or 5 of those sensors have been plain sketchy and untrustworthy, Abbott have been ok with replacing them.
I'd urge you not to jump to conclusions too quickly about them. It can take a few months to figure out libre's quirks and foibles.
I think that new users are sometimes frustrated about the differences between a libre scan and a bg test. But, behind the scenes, there's sometimes perfectly legitimate reasons for those differences.
For example, you say that in the morning libre read 81 and a bg test read 140. Obviously, I don't know the full context in which that happened, but something I'd offer as a general observation from my own experience is that on getting up in the morning, I get a subset of "dawn phenomenon" called "foot on floor" - I'll easily go from 5 to 9 just by getting up as my body prepares itself for the day ahead. I deal with it by a 2 or 3u pin.
How that relates to libre questionable results is that the glucose is released into the bloodstream first and it takes time to then be distributed around the body and seep out through capillaries into the interstitial fluid, which is what libre is measuring, not blood directly.
So, let's say you've got a bit of "foot on floor" going on. It's entirely possible that glucose in blood is x and glucose in interstitial fluid is y, and y is substantially less than x because the glucose in blood hasn't yet got to the interstitial fluid.
Another example would be when I'm trying to correct a high of, say, 8 or 9. I'll inject a few units, and then watch despondently as the libre seems to show no drop to 5 happy land. But then I'll do a bg test and I'm at 6. So the 2u has worked, libre is still showing 9, meter is showing 6, big difference, but it's entirely explainable because changes in bg take time to show up in IF. It's why we need to not just look at the number - we need to think also about what else is going on. In this example, there's active IOB hitting hard, and it's dropping in blood first, and will take time to be reflected in IF later, so I would expect libre and bg to differ.
I think that many new users fail to appreciate the time aspect of this, caused by the fact that bg and IF are different things.
BG, even in non-Ts, isn't actually that stable. It's a constantly moving dynamic system with inputs and outputs, so there's bound to be situations where glucose in blood and in IF differ - for biological reasons, not sensor error.
I was just as frustrated as you are in my first couple of weeks with libre. But I persevered, and after a while it becomes easier to read it. I think many make the mistake of just looking at the number without factoring in the surrounding context, the differences between blood and IF, and failing to consider that time makes a difference.
To make sense of it, it's important to take into account the biology of the relationship between the blood and IF spaces, cross-check against last bg test and where you might expect to be based on last bolus/carbs.
There's third party add-ons such as blucon from Ambrosia Systems and MiaoMiao from High Brilliant Technology, which let you calibrate output from libre. They're small transmitters which are placed on top of libre and ping readings to your phone every 5 mins.You type in a bg reading so that the programme knows that the x it's getting from the sensor means x in terms of bg. My blucon, with an android app xdrip+ has tidied up a few sensors which I would have otherwise have sent back. MiaoMiao is good for iphones as it runs through an ios app, Spike. Plus they do high and low alerts, which makes life on insulin soooo much easier.
But, of course, there are some people for whom these things just don't work at all. I don't know the exact reasons why, but you're basically putting something into your body which isn't meant to be there, so the "foreign body response" kicks in to try to repel it, and even after that's given up the fight against a filament way bigger than they are, it can get clagged up with "biofouling", biological detritus swimming around in the IF, so that glucose can't actually get to the filament to be measured, hence fake lows. I'm not a doc or scientist, but it just seems that some people have biology which just makes them more prone to 'clagging up" sensors than others.
Hope it works out for you eventually, but it can take a bit of time getting used to it.
