There are four categories insurers use:
People with semi-serious illnesses can still take out life insurance, they’ll just pay a higher premium. Chronic illnesses and high-risk professions or hobbies will put a person in the substandard category. A person with a terminal illness will be uninsurable.
Different companies may place you in in different categories, so your premiums can vary greatly depending on your insurer. Once approved, the insurer cannot end your coverage unless you fail to pay.