I stay mum about D at work, but now that I've gone on insulin a couple months ago I may become more open about it in the future, at least with my boss.
Thing is, I travel for 2 months of the year for work - I'll be travelling for a month again toward the end of this year - and that's the only thing that I think will be difficult. I may decide to take on a different role at some point, depending on how that goes, but I think it will be doable.
I stay quiet about it at work because I do feel that in a corporate office (at least mine) the further up the chain you go the more there is a bias in regard to being in shape and the perception of being in good health, ie, bias against anything that could be perceived as impeding your potential job performance. Simply put, for example, some people tend to think - at least subconsciously - that overweight people are going to be lazy employees, or at least less energetic, and that if they can't get their act together with their weight they probably won't be on top of things at work... so I feel like for me the combo of being overweight + D would be a career staller.
I'm T2 and overweight, and I've certainly felt the unspoken bias regarding my weight... I'm hesitant to add to it with D. I'm doing fine in my career (I'm about halfway through my working years and I'm a mid-level manager), but I do believe I'd have gone further by now if I'd been in shape over the years, and I'm fairly certain I've almost reached my career ceiling now until I get in better shape.
Maybe that's just my perception based on what I've experienced and seen, but it certainly seems to be a sad reality, at least in my world. And - just want to add - I work for a large organization that prides itself on diversity, inclusiveness, transparency, etc etc, but this seems to be the last acceptable frontier of quiet discrimination. Not blatantly, but it's there.
I do think that if I told people I'd be supported and it would be fine... but I think it would limit my options in climbing the ladder.