Drinking water and exercising lowers blood glucose. The level of your blood glucose will also determine if it is safe for you to exercise.
Diabetes guidelines say that anyone with type 1 diabetes and a blood glucose of 250 mg/dL or above should check for urine ketones. If you are spilling moderate to large amounts of ketones, you should postpone exercise.
Individuals with blood glucose levels of 300 mg/dL or greater, regardless whether they have type 1 or type 2, should not exercise. I would recommend that before you begin an exercise program to lower your blood glucose you should discuss your concerns with your healthcare provider.