Hi
@Ianhat ,
I think
@helli has covered most of the limitations and first points that are essential for understanding Libre 2.
However, I have found the lag from actual blood glucose to interstitial is a fair bit less than 15mins. This was the lag claimed by Abbott for the original Libre, but for Libre 2 Abbot officially claim the lag averages at 2.4 mins and I find that is more like 5 mins, but not 15. I have a Continuous Glucose Monitor (CGM) piggy backing on Libre so I can see minute by minute what my interstitial is doing, without having to scan and get a flash reading. When I couple those with a finger prick I see this lag quite clearly, both for falling and rising BG.
I particularly agree with
@helli to resist over-reacting when Libre and finger pricks are at odds. In the final analysis believe finger pricks over Libre, but Libre is brilliant at giving you a quicker feel for where your BG is; and when mid range, say 5-8 I don't do much finger pricking - with the one CAVEAT: if, in periods of level, stable BG, my sensor is significantly high or low in relation to actual then I finger prick before food bolus or corrections and use the actual readings for my doses. This week for example, my Libre 2 is consistently reading 2.5 mmol/L high; I can mentally adjust for that as I go about my day, but I won't trust those out of kilter readings for bolus.
Of course this is just me and others will find differences. But I thought it possibly helpful to mention this now; you'll see reference to interstitial lag as 2.4mins on Abbots you tube videos.
Good luck.