i bring it up when its revelvant.
"sorry i called you so late last night, i think i may be on an upswing again. you see i have a mood disorder and i dont always think about stuff like the clock when i have the urge to talk to someone. hope youre not upset about it"
thats an actual conversation ive had. we talked more about it and my friend was very understanding.

use your own judgement and try not to just drop it out of the blue but as i said when its relevant. i know some people have gotten negative reactions. luckily i have only gotten support from friends and loved ones... though disclosure once did keep me from getting a job i wanted.