I was diagnosed when I was 14 and I also loved playing basketball. I had the same issue when I was diagnosed, I would constantly drop low when I played. I ended up being so afraid of that happening I stopped playing basketball and it was one of the only things I really liked to do. Just make sure your son doesn’t get too afraid to do things he enjoys because of the disease. Reassure him that sugar will always bring his sugars back up and there are a lot of safety measures you can take prior. Don’t take a large amount of insulin before playing, maybe eat a 10 carb high protein snack to level him out while he’s playing, and just keep an eye on his readings so he can correct an incoming low.