if you don`t eat sometimes your sugar will go up ,sometimes it drops that`s why you need to eat when you are scheduled to on your diet. stay on your diet and eat the right way and your diabetes will be in control..

When you ate the pizza your liver stored all the starch as it was forced to by the metformin. While you were sleeping the metformin wore off, and the stored sugar in your liver was released, raising your blood sugar. You don’t have to eat to raise it.

Perhaps the carbs in the pizza dough broke down into sugar over night.