To be blunt, they can’t, until you provide them with the information they need to make their assessment that is—and you have to do this to apply for coverage. Some of this information comes from your answers to questions they ask you, and some of it will come from your medical records, which insurance providers typically require you to permit them access to in order to apply. Then there’s the medical exam, which is required during the underwriting process. Included in the medical exam is a blood test, which will often reveal any underlying medical conditions, even if you’re not aware of them.