Hi,
I'm going to Mexico in June and have been fretting, because some of the reviews for relatively cheap insurance that covers diabetes have been quite bad from people who have claimed, and the more reputable insurers wanted £100+. I saw Chewitt's post which reminded me that my boyfriend has a Gold account with Lloyds/TSB which has travel insurance, so decided to check it out. It covers me (ie an extra traveler) as part of his policy, and declared my diabetes without extra cost. It's with AXA too who are a reputable company and it's worldwide cover for unlimited trips up to 31 days.
Think he pays about £12 a month for the account, gets phone insurance and breakdown cover too so we are chuffed!
So definitely think you should look at bank accounts that include insurance as it may be your best bet!
Hope that helps!
Beth