If your blood sugar is 245 you need insulin. Talk to your dr.
You also need to eat low carb and maybe less food at dinner so you can't go so high. If you go this even without eating, then you need insulin.
If your physician will prescribe insulin, Novalog (quick-acting insulin) will do the trick. You have to be careful not to take too much. Some physicians have their patients bring their blood sugars down to a normal range in the evening, with Novalog and then keep it that way with a nightly dose of Lantus. But you need the cooperation and dosing advice of a physician.