Does Anyone Know if a Person Can Get Medical Insurance After Going Through Drug Rehab?

My son went through drug rehab one year ago and is doing great. He has not relapsed at all and has set some quality goals for his life and is pursuing them. He is only 21 years old and is currently in vocational training and cannot afford his own medical insurance at this point in time, but I would like to provide that for him. Does anyone know if he’s eligible since he has a history of drug abuse?