"I began supplying on a regular basis," he said, according to press accounts.
Asked by the judge if he knew what he did was wrong, Douglas replied, "Yes, your honor."
Douglas also pleaded guilty to heroin possession – a charge that resulted from his girlfriend's allegedly smuggling the narcotic to him in a toothbrush while he was under house arrest on the other drug charge.
Douglas, a deejay and actor with a history of drug abuse, was caught in a federal drug investigation last July. After spending six months in a federal lockup, Douglas pled guilty as part of a plea agreement – the details of which were not disclosed.
Sentencing is scheduled for April 27.
In an interview with AARP The Magazine, Michael Douglas described Cameron's incarceration as a wake-up call. "Cameron has a lot of his life ahead," he said. "He now recognizes his own demons and struggles ... He's a tough kid. Still, he's in a federal prison, and you've got some big, bad boys down there."
The Wall Street star also acknowledged his own past demons. "Alcohol was an issue in my life at one point," he said. "A brother died from an overdose a few years ago. Just about any family has someone for whom substance abuse is an issue."