There are four insertion methods. Armpits, belly button (saline only), breast crease, or nipple. Everyone is different, so no one can tell you how much sensation will be lost going through the nipple. Some don't lose any sensation, some lose sensation in one nipple, some nipples become more sensitive, some lose sensation for up to a year then gain it back once the nerves have completely healed. You won't know until it's done.