The best referral I can make is to
http://www.childrenwithdiabetes.com/. They have a very active online community forum and I would suggest his parents will need to dig deep and keep digging to figure out how to manage this disease. It's a tough one, a big balancing act that is always ready to shoot out of control in one direction or another at the least provocation. It's an ongoing education about how to intricately balance multiple everchanging aspects of life.
It's not the same but it's similar in some ways - I had a diabetic cat which, like a small child, could not tell me anything about his symptoms. So I had to learn a lot to figure out how to manage it for him. This juvenile diabetes website was helpful many times in my quest to understand my cat's issues - very good explanations of the processes involved - although there are online resources for people with "sugar" cats and dogs that are obviously more specific to pets.
What I've found is that doctors, including vets, don't really have a huge clue about how to manage nutrition or diabetes -- they just expect the patient to figure it out or, worse, to follow some rote canned "plan" approach which does not work for everyone because everyone is not the same (duh!). There is a lot to figure out. My sister and her two kids have type 2 and they would concur with this assessment about doctors and the "education" offered to new diabetics -- it's very lacking.
Also I just read recent medical research indicates that early intervention with insulin -- and NOT first trying to control it with diet or oral meds -- is now proven to be the best approach and at times they can even reverse it and cause diabetes to go away! So make sure to share that info -- I'm sure not all docs even know as it's quite a recent study result. I do not recall if that study was for type 1 or type 2 though....
Good luck to them.