OK, here are a few of my stories, just so you have an idea of some of the less-than-negative reactions. (I'm straight, but I don't think this matters in this context). These take place over about 6 years.
1. I met someone I really liked at a conference. We spent lots of time together over several days, then communicated very frequently for several months before I had a chance to visit him. When we met again, the feelings were there, but we were both really nervous. I told him that in the morning I would have to wake up at a specific time to take a bunch of pills for a medical condition. He looked seriously relieved, then said that he is also taking pills for a medical condition -- he'd been stressing about hiding them from me at each meal! Telling each other the truth about our health issues was a huge relief for both of us. Now, this guy has a completely different condition, and because of where we live (different countries), things didn't work out between us, but that was probably the nicest way things could have gone.
2. Met a guy I liked, told him after about 4 or 5 dates that I have Crohn's. It turns out that he had Crohn's too, though his was very mild (occasional use of pentasa) and mine is very severe (various meds, now Remicade)! We had a long discussion about esophagoscopies and other stuff over a beer. A few weeks later, the relationship was toast because this guy just couldn't figure out what the hell he was doing.
3. Went on a date with a guy from the Remicade clinic! Nice enough, and no awkward discussion about Crohn's or Remicade, but no sparks.
4. I met someone else and told him after 3 dates about the Crohn's. He said that he had wondered why I seemed so "grounded." It turns out that a close member of his family had been seriously disabled in a freak accident years ago, and he'd spent a lot of time dealing with the fallout from that. This partner was stellar in dealing with my Crohn's-related fatigue and illnesses. We broke up (after 2 years) for other reasons.
5. Just got back on the dating scene after breaking up with guy #4, and met someone I really liked. I told him about the Crohn's on date #3. We had a 4th date scheduled, but he emailed me to move it and then to cancel it because, according to him, there was no chemistry. At first I thought it might have been because of me telling him about the Crohn's, but it is probably more likely because I told him that I would not sleep with him until he submitted his divorce papers! (I have no interest in being dragged through someone's messy divorce, regardless of whether he considers being separated to be the same as divorced).