Greetings JD27076,
Yes you have to be a in a state of grace before going to Communion.
The other posters have posted going to Confession before going to Communion. And this is correct.
Some people may be able to make a Perfect Act of Contrition which does wipe away the eternal guilt that their mortal sins incurred, however this does not preclude or do away with the obligation of going to Confession to confess the mortal sins. An Perfect Act of Contrition is made with the intention of going to Confession as soon as possible. To make an Act of Perfect Contrition is a grace. One must be sorrowful for their sins for no other motive than because their sins offended the love of God.
If I am wrong, please let me know guys. I have problems expressing thoughts sometimes and it may come out confusing. I shall look up some sources and when I find them I shall post them back to this thread.
God bless.
Anathama Sit