Welcome to the Forum!
In GB it's the average of your daily inputs, as shown in the graph purple line.
Read through the first three threads in the Type 2 Section, when you get a chance, if you have not already done so. These threads will most-likely help you a lot. Self education is one of the keys to successful management of your diabetes, along with a healthy / sensible diet and exercise. Basically, diabetes requires a life-style change for the better. Good luck with your control and management.