When on insulin its always a good idea to test during the night if you wake, if anything it gives you some piece of mind so you can fall back to sleep again if your bg levels are in range, but definitely keep some fast-acting glucose by your bed at all times in the event that you do have a hypo, liquid glucose like GlucoJuice works extremely fast.
To help prevent the night peeing don't drink anything in the later hours of the evening, especially caffeinated drinks. Best wishes.