3 year old keeps peeing the bed

My soon to be 3year old keeps peeing himself at night. I've tried cutting drinks 2 hours before bed, make him pee two to three times within 2 hours before bed and right before he lays down, tried rewarding patience and he still does it. Sometimes even twice I night. I can't put him in diapers or pull ups or he'll start to pee himself throughout the day . Need honest and actually helpful advice how to get him to stop or not have it happen so often.