Using xDrip+ and Nightscout, calibrating xDrip+ properly to account for sensor inaccuracy on any given day (using a good meter) and using that system to make decisions that relate to your health requires significant learning to be sure you're doing it right. The official Libre 2 app is an approved https://www.metooo.co.uk/u/68513e35dbefc27c34f96716