Your destination will dictate the type of cover required. If you’re travelling to countries where health costs are high, you may want to consider purchasing a policy that has unlimited~ medical cover. In countries that have a reciprocal agreement with Medicare, you will be entitled to benefits similar to Medicare for necessary medical and public hospital treatment.
All policies have restrictions for pre-existing medical conditions. Where asked, you must inform the insurer of any pre-existing medical conditions before you buy your insurance. Failing to do so may result in your entire insurance policy (not just your medical cover) being cancelled or claims refused.