I am also a type 1 diabetic. I have only done tandom jumps (2 of them yeah im a little slow at getting around to doing more).
Not to scold you, but they higher numbers can cause MANY problems later in life (blindness, failure of organs, amputations. blah blah blah.. i know your dr has probably warned you. (sorry).
Now back to the question. test, test, test. Im on a pump. when i jumped i would test before and after my jump. I would also suspend my pump so i dont have a chance of going low during my jump. I would test and do any correction needed once i landed. I know the waivers at the DZ i went to said something about diabetics (yeah i overlooked that one :) )