I'm only a few crashes away from Type 2 myself. Being "pre-diabetic" is basically keeping the diabetic diet and a mild daily oral med. If what was discovered about the links between brain issues and Type 2 diabetes in old age is proven, it's well worth it to keep to the diet and exercise as best as possible.
Lifeclinic has a page devoted mostly to starting and maintaining an exercise routine (though I think using public transportation daily forces more than enough walking and stair climbing to satisfy the requirements) and some general diet tips. It's as good a place to start as any (and if you find diabetes information without a corporate sponsor attached to it, even indirectly, I'd love to know about it).