I keep it a secret for about 20 years. I used to lie like crazy to friends, relatives, and work about what was going on. I finally went out on disability which eliminated the need to lie at work. My husband knows of course...he is my total caregiver and goes with me to appts, managing my meds, etc.
I got pretty sick of lying to people. So I gradually started telling people that were close friends. They are all still friends so I guess they either suspected or knew. I even wrote a few letters to friends I had dropped away from because I did some embarrassing manic things around them and couldn't face them. I heard back from two of them and have wonderfully rekindled those relationships. I don't tell new friends right away, or people like hairdressers etc. My nieighbors don't know as we are friendly but not friends with them. So I disclose to those close, but not all.
I respect anyone and support everyone's right to choose disclosure or not.