Sleep and the Dawn phenomenon are the unseen gremlins with BSLs.
Sleep has a habit of restoring your levels without you having to eat for such a long period, the body renews it's systems and tries to keep you healthier. If like me you have restless sleep, it can knock your levels all over the place and you don't get that renewal.
What I've read about DP(quick learner!) that also throws your BSLs all over the place because it reads as a fasting blood that is too high!
Once you've had your first meal you do normally return to a normalish reading!
It's your body,your tastes, your diet, you know what to do!
The thing about T2 is you will get ups and downs and that the low carb diet is the way to go, along with exercise.
If I don't eat my BSLs stay between 4 & 5, and don't move. It is only when I eat carbs and sugar does my body react.