How do I tell my coworker that he might have cluttering speech disorder?

How do I tell my coworker that he might have cluttering speech disorder? I have a coworker who I honestly have a hard time understanding when he talks. At first I thought it was just me or my hearing, but it happens pretty often. I’m not trying to diagnose him or anything, I just don’t want to come off rude or make things awkward at work. Is this something you’d ever bring up, or is it better to just ask him to repeat himself and leave it alone?