S.D.
My son, also adhd, has done this too. He might really be hungry. Offer him a bedtime snack (healthy one). I used to give mine crackers and a glass of milk to help him get ready to sleep. Tell him that he once he is in bed he needs to stay there. He must get all of his night time stuff done before bedtime, snack, bathroom, brushing teeth, water. If he gets up past bedtime, there will be a consequence. If he's getting sweets without permission, they'll go in the trash.
This worked with my son. Also, you may want to positively reinforce him getting in bed and staying there by rewarding him the next day. Maybe then he can have a sweet.
I'm afraid if you completely take away all sweets and don't allow them in moderation, they can become a "forbidden fruit." It's just my opinion, but I think teaching moderation and impulse control is better than teaching deprivation. The reason many people on diets fail is because they feel deprived.