There's just no substitute for frequent self-testing. It's the only real way to keep a handle on which foods are more problematic, and whether the diabetic is really controlling the disease. You either control it, or I guarantee it controls you.
I know test strips are expensive, but there are cheaper brands that will at least allow you to get an idea of what your sugar is doing, and I can't recommend getting your own meter enough. I think every newly diagnosed diabetic should test five times per day. If you do, then you know very quickly what's going on with your body, and you can start learning ways to help yourself.
Early control means fewer complications in the long-haul.