I think a lot of women can relate and have eventually had that horrible test. I hope they also cultured you for some kind of bacteria or fungus.
If you do not have an anatomical abnormality congenital or acquired, there are old fashioned remedies. My own mother once was put on this horrible diet of only 100% pure grape juice for three weeks to get cured of a really bad case.
The most common, though, and as a diabetic you have to taken the unsweetened form of it is cranberry juice. I have done this for a day or so by buying a couple pounds of fresh cranberries (or fresh frozen), boiling them in an equal volume of water for a few minutes, straining and drinking the juice (which can be cut with water) and eating the pulp. This is not as delicious as dried sweetened cranberries but it sure works. Here's a website that talks about how cranberry works
http://doctormurray.com/health-conditions/bladder-infection-cystitis/