FreeStyle Libre experiences

@Pianoplayer7008, we rely heavily on our CGM at all times. Yet, I have documented, and sometimes posted, multiple examples of cases where, for us, there will be a systematic error between the two. For instance, for us, after injecting for a meal and waiting until we have turned the corner, once my sons starts to eat there will ALWAYS be a significant difference btween the CGM and the BG meter, for at least 25 to 30 minutes, sometimes longer.

The differences come from at least two sources:

  • the CGM relies on interstitial fluid, while the BG meter uses streaming blood

  • the CGM algorithm is trying to estimate numbers, and makes adjustment calculations every read. These calculations actually lead to some errors when there is change in levels.

Here, likely, the BG is going up, so the Libre is lagging I am guessing

I am assuming that when you say “steady” it means a horizontal arrow. I find that these arrows are gross approximations of the actual curve. If you had a way to picture the curve in your head your eye would be able to estimate trends a lot better than the arrows. I am thinking that, here, the meter has still not caught up to the actual blood measurement, and is still climbing slowly.

By then, typically our CGM and our BG meter are reasonably in sync. Yours appears to be as well, and the residual difference can be due to either one of the two or both.

Btw, your ReliOn is not a bad meter! It is not as precise as the Contour One, but it is the best of the cheaper strip systems (check @MaryPat’s thread here: The best BG glucose meter that your insurance will pay for) so it is one that I would be happy to rely on.

All BG meters, of course, have some noise, so there is always a bit of jumping up and down in the data. If you are willing to spend about 50 strips to figure out exactly how it impacts you, I will post in the next few minutes a different thread that shows what you can do to know exactly what you are facing.

To my eye, your results are very good, and, in fact, better than I expected. This is a very good performance for a self-calibrated meter.

[EDIT] I posted a method to calculate your average BG meter error here: How to estimate your BG meter's noise