I've been in the same position when I was your age. A lot of us were, and there will be more to follow. It's a natural phase of acceptance.
The only advice I can give you is to just stop and think about the situation. We are lucky to be alive, life is so precious. Unfortunately we have gotten this condition that is annoying & inconvenient at times, but lets do our best to make it a great life. I'm not looking down from any high horse or anything like that, I was in the exact same position as you many times, but I have thought myself to accept the conditionI have been given.
Do your best with your diabetes, and you will get the best out of life. In a few years you will look back and know exactly what I am talking about. Best of luck going forward and don't leave diabetes get the better of you, you own the diabetes it doesn't own you.
Good luck in your exams.