Can I require my fiancé to show me his finances for a prenup?

I’m engaged and my fiancé wants me to sign a prenuptial agreement. He says he’ll have his lawyer prepare it and all I need to do is sign. My concern is that I don’t know what I’m possibly giving up. He’s very private about his finances, we don’t have joint accounts, and he doesn’t want to have them even after we marry. He says that as long as he’s taking care of all the bills, it shouldn’t matter what money or property he has coming into the marriage. Can I make him disclose his financial situation before I sign a prenup? I am not only concerned about what I might be losing if we ever did divorce, I’m also concerned about being responsible for any debt that he might have now that I don’t know about.