Do you budget your money out and track every transaction? It sucks to be in that situation, but there are always things you can do to improve it.
It's hard to go bankrupt from this directly because they're careful not to lend you more than you can pay back. It doesn't always work, of course, but they do a decent job of figuring that out.
Note that a lot of medical bankruptcies aren't bankruptcies due to medical bills alone, but are people with insurance who go bankrupt due to a combination of deductibles, additional non-medical expenses related to the illness, and a sudden reduction in their ability to work. Having a bunch of credit card debt instead of a bunch of savings could easily put someone in that situation, so the two probably work together a lot.
http://www.theatlantic.com/magazine/archive/2016/05/my-secre...