One reason the Affordable Care Act was passed was to give everyone health insurance, even if they have a preexisting condition. Diabetes, pregnancy, congenital defects and more don't necessarily have to be covered, but someone cannot be denied a plan because of a previous malady. Although flawed, the ACA's coverage of preexisting conditions was a huge victory for uninsured Americans.
The Affordable Care Act covers pre-exisiting conditions. This was one thing President Obama wanted in the law, and so did most members of the Democratic parties. It is now against the law to refuse insurance coverage to anybody with a pre-existing condition. This is another reason why Obamacare will eventually be seen as an important piece of legislation.