Sounds like you have a good doc. A1C is a good measure of how your glucose levels are working, but it isn’t included in the normal test, so good on her for ordering it. Probably the best measure is fasting insulin, but very few doctors look at that. By best, I just mean it catches problems earlier, and standard glucose is really easy to take, even at home, but you can spike it just by gettin nervous to give blood, or angry at some asshole driving badly on the way to give your test. A1C can’t be moved by those kinds of things.
Obviously, diet matters, but adding muscle is a really good counter to high-ish glucose. Muscle acts like a heat sink for glucose, and the more of it you have, the more you can sink.