Hi Paiste,
Your car insurance should not be affected by diabetes - it would not be legal for them to increase it on that basis. My car insurance did not rise when I informed them I'd started using insulin and had a restricted license. They didn't even apply an admin charge to alter the details, although they would have been within their rights to. Neither did it increase when it came to my renewal a couple of months later. Seriously, if they are trying to increase yours on this basis, shop around - you will find other companies who do not increase the premium for being diabetic.
Smidge