Probably the main thing to consider is whether he is correctly placed within the school system. If he displays ADHD alone, and this condition is treated successfully, there is no question he should be able to function successfully. Your brief descrition invites questions about whether he displays some co-morbid condition alongside the ADHD and whether the ADHD itself is successfully treated. If he is not on an IEP it would make sense to request an evaluation and this might identify the need for an IEP. Then the suitability of his current program could be examined.
It's really common for children w/ ADHD to have Oppositinal Defiance disorder. (Sorry i couldn't get oppositinal spelled correctly) Look it up & see if it fits your son's behavioral issues. It could also be something as simple as diet. An IEP is also a must. Check & see if his current Dr. is an ADD/ADHD specialist. I myself am ADD/ADHD along w/ all 3 of my kids & they are all different. It's rough, but the answer is out there. I have read so much that it became an obsession ya know? The scope of all the things possible w/ ADD/ADHD is HUGE. I'll Pray that u find the right answers for your son. Always remember that being who he is, is difficult for him. He has so much that goes on in his head that he may have a hard time keeping it straight. Being disruptive & arguing, misbehaving help his brain to work more normal & makes him feel better. So a lot of times they will keep it going. He may feel like he can't do anything right & it may actually be painful & make him sad not being able to control some of his actions. A lot of hugs & talks & time together helps so much. I figured out that the connection between us was key in getting them to talk to me about things they were ashamed of because of the ADD/ADHD. Talking to them simply about they're ADD/ADHD & how it doesn't mean they are stupid,but most likely are very smart makes them feel better. It helps them to understand it & to be able to begin dealing w/ their ADD/ADHD. He needs to know that you love & care about him even though they have these issues. Obviously I don't know what kind of mommy u are,but since you are on here looking for advice it's probably a safe bet that you are a good one. I have found w/ my 11 yr old that being a positive mom helped him & I. What I mean is.... Whenever I would say no to him he would get so angry & it really made things hard. I started answering him positively. I would say "You absolutely can..... after you take your shower. The first time I did that it stopped him in his tracks. He looked at me paused & said ok cool, thanks mom... Who was that kid??? right!!! I wish you both all the best