I think it's best to ask the person directly what they want you to do. Some people want to be "outed" and some don't. Some people want special treatment, some don't. But the general consensus is to just treat them like normal people. Don't finish their sentences (do you finish everyone else's sentences? It's annoying and you probably don't know this person well enough to know what they are going to say before they say it) And maintain eye contact (just like you probably do with everyone else). Be patient. Be kind. Don't joke about it. Also, one of the things my boss did was give me extra time to practice my presentations in front of him. He was patient with me, maintained eye contact and didn't treat me any different than the other employees. He even has given me speaking oppurtunities in the past. "Hey, I would really like you to present this data to the team. Do you mind doing it?" Instead of just telling me that I have to do it. Basically, he didn't throw me to the wolves, asked me first and gave me ample time to prepare.