Who is this person to you?
Without knowing who this person is to you, i will make some comments and then wait for you to come online. It may not be necessary to tip toe around them as i dont believe that helps anyone but at the same time, I don't believe forcing the truth upon them is the right way to go either as it could put undue strain on the relationship.
Unless this individual believes there is an issue and wants to get help then it might be difficult to suggest it if you dont have a close relationship.
If on the other hand you have a close relationship with this person and you can see how it is altering yours and others around them, you might be able to sit down with this person and let them know what you see and feel while around them and offer to help them in any way you can.