The word on insurance providers denying people who've participated in med. studies?

I was talking to a friend last night who’s participating in a medical study at the medical university in my home town. It sounds interesting, and it pays $500 for three visits.

I’m only in town for two months and need to make as much money as I can before I move to Asia. I want to participate in the study, though I’ve heard that insurance providers can deny you coverage if they find out you’ve participated in medical research.

If I go up there, will this come back to haunt me one day?

How would they find out? :confused:

I don’t know. That’s part of what I’m asking.

This is just what I’ve been told from people.

Well, I have participated in dozens of studies as a normal control. I’ve never had a problem with insurance. Hope someone with an authorative answer shows up.