I was diagnosed when I was 12. I was getting up maybe ever 2 to 3 hours to get a drink and go to the bathroom. I was diagnosed by urine test. Urine tests look for glucose and ketones. You want to tell the nurse when you call about the teacher's observations as it does carry a bit of weight when trying to get an appointment sooner rather then later.
This is a very portable disease and only becomes debilitating when you DON'T take care of it. If your son does have JD help him to take responsibility for it. Give him power to help himself. Of course you are going to help him regulate his sugars in the beginning but again, give him ownership so that he will learn about his body. Finding out when you young is much better, IMHO, then when you are older. Yes, your body suffers longer, however, telling a 65 year old that they need to change the way they have been eating for the last 65 years is harder then helping your 7 year old adjust to changes that will be better for your family all around. This also does not mean that your child will never have candy or cake again. He will of course! You learn how to adjust your insulin for exercise and sweets. When we go to WDW I ALWAYS have a Mickey Bar! However, I would NEVER have a cinnebon. The smell of them makes my teeth itch.

You also learn how to have 3 m&ms vs a whole bag! It can be done.
Yes, low blood sugars and High blood sugars are terrible. They are scarey and they make you sick and I still have pity parties about it, however, I always remind myself that there is no alternitive available if I want to live a healthy life which I do for the most part.
Good luck with your DS. Please PM me if you have any questions. They have great things out now like insulin pumps which make life alot easier to control your blood sugar. These pumps even have sensors in them that measure your blood sugar as well.
Take care!
E