
Sorry to hear that. I'm sure you must be feeling terribly worried and a bit scared but there is no reason that your son won't be able to continue to do all the things he did before and more besides once his routine is established.
My friend has been diabetic since she was 10 and is now 43. She is in excellent health and lives a very full and active life :) She also has to inject up to 5 times a day but the routine is second nature to her. I helped with her injections for a while when she hurt her wrist and couldn't do it herself and it's not nearly as bad as it seems (easy for me to say, I wasn't at the sharp end!!). She uses a device like a pen where she sets the dose, sticks the needle in and presses a button on the top which is far less scary than the thought of hypodermic needles etc.
Lots of help and advice will be available from the diabetic clinic at the hospital. Ask plenty of questions and try not to worry too much :)