I would say it depends on the situation and how long/well I know the person. When I was teaching I would explicitly inform them I have a speech impediment and that it impacts me more than them. People often tell me they don't notice it, but if acquaintances or friends notice and make a comment or "joke," I say I'm disabled and that I can't control my fluency. Had a coworker say "dude do you have a stutter or something?". "... Yes. Yes I do, thank you for pointing something out that I already know." Shut him up pretty quickly.