Personally the best advice that I can give to any student going back to school is to tell everyone about your diabetes. Don't assume that teachers, coaches or teammates know. It took me a longtime to get the nerve to speak to teachers, I didn't do it until I was going back to college at the age of 28 but when I did so I wished that I had done it while I was in high school. The more people know the better, I often found that the teachers would ask me a lot of questions about my diabetes because they care. They want to know the signs of a high or low blood sugar because they want you to do well as a student and as a person that is conquering diabetes.
When it comes to sports and after school activities don't be like me and tell make sure that your coaches know. It still bothers me that a coach I had in high school asked me "When did you get diabetes?" he asked me this two years ago, I was 30, I have been a diabetes conquerer since I was 8. I can't imagine what would have happened had I had an extreme low blood sugar at basketball practice or during a game. Don't assume that because you give all of your paperwork to the nurse and that the forms are given to coaches that they know. I had all of my paper work in and my coaches never knew, it is not a piece of papers responsibility to tell a coach, it is yours. Just like a teacher a coach cares about his or her student athletes.
Finally, tell your friends. Your close friends may already know all about your diabetes but people make new friends and if you are at college you may not know many people. If they are truly your friends they will care and want to learn more. If they say "Whatever" then it may be a good idea to find new friends. A response like that from anyone should sound an alarm that tells you this person isn't good to be around.
The first day of school is the best day to talk to anyone and everyone about diabetes, from the school nurse to teachers. It only takes thirty seconds and lasts the entire year. Knowledge is power and the more people know the better off everyone conquering diabetes will be!!