Libre 2 and BG lows reporting

[CathyFP]

Hi,
I’m just wondering whether this is normal Libre2 reporting? This evening before dinner my BG fell to 3.6 mmol /L and I can see this on my log for the day as I scanned my sensor , however the low doesn’t show on my’Low glucose events report or on my daily graph. How low does BG have to fall to be included in these reports. I also find some highs don’t seem to be accurately reflected on the daily graph.

Thanks for any help with this

 

[Bruce Stephens]

How low does BG have to fall to be included in these reports.

I think it's because those things (and all the Time in Range calculations) are based on the 96 values for each day (1 every 15 minutes) which are also used for the graph. So it's easy enough for a low or high not to be counted if it happens at the wrong time and if it's short-lived enough. (Since such things have to be short lived not to be counted, I think it's no big deal.) It may also be that those calculations are made from actual readings whereas what you get from scanning might be a prediction, which might also cause a scan to give a lower value than is recorded or shown on the graph.

I'm speculating, but I think that explanation makes sense.

 

[helli]

Also speculating but the "missing low" could be due to the prediction Libre makes for the current BG.
CGMs di not measure blood. They measure interstitial fluid. A change in BG is reflected in a change in interstitial fluid reading 15 minutes later. Libre accommodates this delay by "predicting" the current BG by extrapolating the current trend on the BG graphs. If the trend changes direction in that 15 minutes, the prediction can be wrong. Libre will, therefore, correct it's prediction when it finds out.
Given the low was recorded before you ate, it is possible that eating allowed your BG graph to turn around before you actually met that low reading.

 

[Lucyr]

It needs to be low on a 15 minute average to count. A 3.6 that you treated quickly likely won’t count.

 

[Tdm]

I think itxwill be a prediction, which libre realises it git wrong and promptly pretends never happened.
Libre can be a bit of a drama queen