The 49-year-old singer says his heart goes out to T.I. and Mars.
DeBarge says he knows that people experiment with drugs and that he did so because he was curious.
Earlier this month, Los Angeles police caught T.I. with several pills confirmed to be a controlled substance.
Mars was arrested this week in Las Vegas for allegedly possessing cocaine.
DeBarge was jailed for two years following a 2008 drug possession arrest. He's planning the release of "Second Chance," his first album in 16 years.