Yes, but as a result of that algorithm, there are times when your Libre reading can be 30 mins behind actual BG. Ie when rate of change is happening or BG levels are completely changing direction.
When levels are just tootling along nicely and reasonably stable and in range, the algorithm predicts quite nicely what your BG is likely to be by extrapolating forward the 15 mins, but when levels are changing fast then all bets are off and Libre will very easily exaggerate both lows and highs. I know you know this
@helli but just wanting to clarify for others. As a result, the key thing to remember is that you should only really compare Libre with a finger prick when your levels are pretty stable and not when there are significant factors in your system causing them to change .... ie you injected insulin recently or ate recently.... or you are experiencing Foot on the Floor syndrome/Dawn Phenomenon on a morning or during/after exercise.
This is why it is so important to check with a finger prick following a hypo treatment rather than rely on Libre, because Libre will almost always show your levels continuing to drop after 15 mins because it is continuing to extrapolate the downwards trend whereas your BG levels will usually have come back up after 15 mins. If you go by the Libre in this situation, you will almost always end up double treating a hypo that doesn't need it and end up high and then you are on "the rollercoaster".
So as
@helli says in order to get the most from Libre you have to understand it's limitations, including compression lows and how that algorithm extrapolation works to make up the lag on interstitial fluid and when that extrapolation makes it unreliable and for how long (usually 30-45mins) for it to catch up in that situation. And when it is reasonable to assess it's accuracy against a finger prick. I always wait until my levels are stable for about an hour before I do a comparison although these days I rarely finger prick because Libre works incredibly well for me, now I understand it...... and have learned not to lie on it in my sleep
🙄 or try to (accidentally) scrub it off in the shower!
or walk into door jambs!!
The stock response from Abbott is to replace the sensor making people believe the sensors are unreliable, but in my experience, the sensor is rarely the problem. Problems with the LibreLink app, their phone in general and people's understanding/expectation and the sensor coming loose due to getting caught on a variety of things or occasionally the adhesive failing, are the most common problems and unfortunately the customer services staff are not capable of comprehensively dealing with these issues, so they send another sensor out which I believe are the cheapest part of the system, so the easiest option for Abbott. There are however some people whose body chemistry does not get along with the Libre and these people may be better with a different system like the Dexcom.
Not saying the sensors never fail, but mostly failure is due to other issues.
