No, just addicts in general. People will usually be reasonably comfortable telling their doctor that "yeah I have a few drinks a week" because alcohol is socially acceptable. They may not be truthful about the level of their abuse or accept the help in good faith but at least their physician can monitor them for signs that the habit is becoming harmful.Aren't we talking about someone seeking help? I don't know a single doctor that wouldn't help an addict whatever the substance, when it comes to seeking help I think that the issue has more to do with people accepting that they have an issue in the first place, then they may seek and accept help. There are millions of alcoholics that can't be helped by their doctors because they refuse to be helped and I don't see why it would be different for other substances.
You can bet that not many of those addicted to illicit substances will tell their doctor they shoot up four days a week or do cocaine from morning til night and the habit will go unnoticed until a serious issue occurs. This means that the person isn't getting guidance and advice that could benefit them because they are afraid to be open about their habits. This is due to the socially unacceptable nature and illegal status of those drugs.