Having your son evaluated by a child psychologist or child psychiatrist is an excellent place to start. Ideally, it would be someone in that field who already works with the clinic that watches your son’s diabetes with you. This may not simply be “ADD”, but rather a more serious behavior/rebelliousness through which he is showing his anger about having diabetes. These issues need to be resolved.
Perhaps if he were on a flexible insulin regimen that allows him to eat at variable times, he might feel a bit more in control of his life. Diabetes management, obviously can be very regimented, but if he can carb count, then he might want to explore going on multiple daily injections (MDI) with long-acting insulin (like Ultralente or Lantus [insulin glargine]) along with short-acting insulin (Regular, Humalog, or Novolog) when he eats. This would be a potential precursor to an insulin pump (for much less money).
DS