Martin, if you look at the bottom of this page, there are a series of posts related to thrush which might help you.
The normal advice for controlling thrush is usually related to bringing blood glucose down to normal levels.
I'm not a type 1, so I can't really advise you further.
Also, if you type the word "thrush" into the search box at the top of the screen, it should bring up other posts about the subject.
Best wishes,