If he does it all the time then it sounds like racism. I know a woman and she says she's bipolar but is generally just horrible and says really thoughtless stuff to people all the time. I'm never sure if it's part of her illness or not, as personally I've done and said some bad things but when I've calmed down (or sometimes while I'm saying it) I'm realising I'm overstepping the mark but I can't stop myself.
Sorry I know this doesn't help, but I agree with the others going about and saying hurtful things all the time (to me anyway) doesn't seem like bipolar, and if it's just directed at you then he might just be racist.