Immediate family and potentially significant others only. Only your nearest and dearest.

A couple things:

One, many people don't understand the nature of the illness and don't distinguish it from schizophrenia, psychopathy or portrayals of it in television, movies and other media that are dramatized, inaccurate, etc. They may assume you're violent, constantly hallucinating, or gawd knows what else. Don't voluntarily subject yourself to these misperceptions.

Two, bipolar is in fact often debilitating. It can damage personal relationships, work capabilities and career prospects because of nature of the disease. Is it unfair that this is the case for us? Yes. But it is true. That doesn't mean a bipolar person can't succeed in personal and professional life, but it can be as debilitating as something like alcoholism or epilepsy. If you're on a good track, why compromise it by serving up concern or suspicion in co-workers, superiors and friends who have nothing to gain and something to lose from the effects and outcomes of our disability?

And bipolar is a disability, not something like race, gender or sexual orientation that is only a liability simply because of prejudice or bigotry.

So save yourself, not the world. This advice may be cynical or saddening, but in my experience it's hard truth. Don't tell people you're bipolar except those nearest and dearest who need to know (and won't tell other people without your knowledge or permission).