There are life insurance plans available for people with health issues, including fully underwritten life insurance policies, no exam life insurance plans, and guaranteed issue life insurance.
The fewer health questions or requirements for approval, the higher the premium charged, usually, because they may accept applicants who may otherwise be unable to get insured for life insurance.
If you do have a health issue and have been denied life insurance already, you may want to consider guaranteed issue life insurance coverage which cannot deny you coverage due to health problems.