"We're supposed to be where the health care comes from, right? We're supposed to be the ones who make it better. And I couldn't even take care of myself," Giles said.
Like Giles, however, doctors can get help.
"Every state has a formal program to provide treatment and supervision for physicians. And in fact these programs are a model for what everyone should have," Rosenbloom said.
And medical professionals say doctors have an especially high rate of success when it comes to staying clean.
"Five years after doctors go through these programs, more than three quarters of them are still practicing medicine and clean of their alcohol or drug addiction," Rosenbloom said.
Meanwhile, Parker faces 34 years in prison if convicted of the three federal drug charges: tampering with a consumer product, creating a counterfeit substance and obtaining a narcotic by deceit.
Parker could wind up with a life sentence in federal prison if prosecutors can prove to a jury that she caused patients serious bodily injury or death.
ABC News' Christine Brouwer contributed to this report.