FYI, preexisting conditions stopped being a major issue with heath insurance after the Affordable Care Act (Obama Care) got passed: https://www.policygenius.com/health-insurance/pre-existing-c...
Insurers cannot deny health coverage, cannot charge higher costs, or subject people with pre-existing conditions to a waiting period
You may be better off getting life/long term care insurance before getting tested, but other than that there is little reason to avoid being tested.