I have very mild asthma and my partner has type 2 diabetes. My asthma isn't very bad, but I'd noticed that the insurance companies seem to be clamping down on the pre-existing medical conditions they cover. I went with a company called Citybond (www.citybond.co.uk) You have to fill in a questionnaire about the illness, including an explanation of what medication is taken, and how bad the condition is. They come back to you with a yes/no answer and a premium. I hope this helps.