Hello Jo:
Low is the only problem to be “concerned” about for several reasons. Behind the wheel, unconsciousness can be death or worse. High, takes a very long time to reach that same point. Readings can be quite polite ie say “HI” and though we won’t feel like running a marathon, we can still function the minimal amount which driving requires anyway.
However I would offer that he can also be a teen as well as a diabetic at the same time. Diabetes is by no means necessarily the problem… re: his attention. But yes driving over 200 is basicly irrelevent.
Two points for consideration. 1) put a bottle of soda in the car for emergency ONLY. Not to be drunk unless he is low… only then, only for him. A-L-W-A-Y-S 2) As a young person, he MUST do the testing and there can be no debate about it. He must or he cannot drive. Its pure self protection on your part, but a good habit.
1,000 speeding tickets fine (not), but, if he does not test you have his head in a jar…
Stuart