Diet can have a great effect on your Bg levels, so what you eat is important. Without knowing what types of things you are consuming we can only hazard a guess as to why the levels are higher. Over indulging can raise the levels.
As for exercise, it can both raise and also lower your Bg levels. See previous posts on the subject of exercise on the Forum. It really all depends on the type, the intensity and many other variables. Without some further information we can't really help you out ?
Ken