Druggie Drama

Yeah, it's off topic, but hey I need to vent. The thing is my sister is an addict. She has three kids, two of whom hate her and one who is fast becoming sick of her. She has her own apartment, which she won't keep remotely clean, but is living with my parents, who also pay the bills for said apartment.
Why? Well, she does have some medical issues. Some were brought on by the drug use, but she's also diabetic, though she doesn't even try to eat right. The real reason is because she is such a bad addict she can't be left alone.
I've had calls from my mother to come pick her up out of the tub, where she's passed out in the middle of a shower. My Mom found her with the water still running, out cold. It took thirty minutes after I got there to get her halfway awake. She passes out over the stove, while eating, on the toilet, anywhere and everywhere. She's passed out with her face literally in a bowl of cake batter. She's passed out with hair coloring on her hair - hair that she pulled a Britney Spears on and pretty much shaved to the crown with a few long strands on top. She had decided to give herself a haircut while wild. She's left the stove on and my parents have woken up to the smell of smoke. She's a danger to herself and everyone else.
Her docs can't/won't put her in rehab, the last rehab she went to didn't even consider her problem "that bad"because it was prescription drugs rather than street drugs like cocaine or heroine. What prompted the last rehab visit was driving my niece to court over not getting her to school and being so obviously high at the truancy hearing that she was arrested for public intoxication.
They just let her back out of the hospital today, which she was in for four days getting test to rule out anything medical causing this. We are all about to go nuts with this. It's so draining, every day, to get the "help me get her up" or "I can't take this" calls from my Mom. I can only imagine how my parents feel living with her! My Dad has aged ten years in the last two years, and both of them are so stressed out and sleep deprived. What is worse is her children having to suffer.
I know it sounds cold, and I don't want anything to happen to her, but she is choosing to do this to herself, and as long as she does I feel like she should have to fend for herself. Maybe then she'll want to clean up her act, but if not, it will save my parents the daily struggle they're in now. It's all day, every day Druggie Drama, and it's too much.