All depends if your job might be at risk if people found out.... And, yes, I know all about Equality Act etc, but in some cases, self preservation works best. Perhaps having lost my rights to drive minibuses, serve in armed forces, SCUBA dive professionally, and never having needed any intervention from anyone else etc makes me a bit more secretive than is appropriate for others.
I prefer to wait until people have seen me deal with some difficult situations eg very bad weather, tough physical work, irregular meal times etc without help from anyone else, before letting them know. It's particularly fun to see the reactions of people with medical qualifications eg a work colleague know me as the only person ever to have skiied to work, but after leaving, I told him about T1D - he admitted to surprise, but said he reckoned I was the sort of person who could cope, which seemed a wholly appropriate reaction.