travel insurance illness

When getting travel insurance, I must reveal all my diseases?
Sometimes travel abroad and buy travel insurance. I do it by phone and do not ask many questions. But then I have not read the small print. I saw the movie Sicko and realized that they can refuse to pay their medical bills if you not disclose any conditions that may have even if injury is unrelated to your doctor, while under insurance. To be specific, even travel insurance gives you a hard time when you want to pay – so I heard. Is it true and how to purchase travel insurance. Mine just expired. Thank you.
Tell them everything. Nothing worse than paying for insurance you do not pay when they need it. Speaking of which, to buy mine now …
International Medical Group ®, Inc. – IMG ® Travel Health Insurance