Friend is "100% sure" he's autistic. I'm skeptical.

He claims that his senses are easily overwhelmed by his environment, which I get, but instead of shutting down like I do he gets really manic and has no filter. I know not all autists are the same, but his social interactions really make me unsure. He just talks and talks and talks to all kinds of people, even strangers, advertises pretty much everything about himself (no filter again) and honestly drives me (who is more reserved and quiet unless around people I know very well) insane sometimes. He's definitely got something diagnosable about him (as well as having depression and anxiety like me), but I'm skeptical that it would be anything on the autism spectrum.

He can be a bit fidgety as well, but not as much as me. Once again, his social interactions don't really seem "autistic" to me. His tone of voice is very natural compared to most autistic folks I've met and he doesn't seem like he has to manually process parts of social interaction like I do. If he did, I'm not so sure he'd be able to talk to new people (something exhausting for me most of the time) for sometimes hours on end. I didn't really word this post as well as I'd like to. Friend is sure he's autistic, I'm skeptical, but I guess I could be wrong. What do you guys think? Also feel free to ask if anything in this clusterfuck of a post was unclear.

Update: My friend has told me that his doctor says he is not autistic.