Being told you are "borderline" was not doing you a big favor. From everything I have read, you are either diabetic or not. The A1c blood test is definitive. 5.5 or lower is normal. Anything higher is diabetic. Some doctors are hesitant to tell their patients that they are Type 2 diabetic and try to ease them into the idea with the "borderline" diagnosis. Take this seriously. The long term side effects of uncontrolled high blood sugar are very serious.
Basically, eat healthy foods. Gluten free has nothing whatsoever to do with a Type 2 diabetic diet, unless, of course, you are gluten intolerant. There is a definitive medical test for that as well. No need to guess. You need to count carbs. A baked potato or a brownie is pretty much all the same to a diabetic and their blood sugar levels - lots of carbs. Of course, a potato with skin (and not a lot of butter, sour cream, cheese, etc.) will be healthier than a brownie. If you follow the rules of healthy eating - low fat, limited amounts of red meat, whole grain, plenty of fruits and veggies - you will have the basics of a diabetic diet. Think Weight Watchers, if you are familiar with their program. Don't wig out. You can have treats in moderation. If you have a potato at dinner, then no dinner rolls. Not a giant 1 lb. potato, either. Above all, completely kiss goodbye sugared drinks - sodas and sweet tea. Sugar free alternatives are okay, again in moderation. The American Diabetes Association web site has plenty of good information. Get regular exercise - walking is fine. Strive to maintain a healthy weight.
I have been a Type 2 diabetic for 16 years. I take oral meds and have been able to manage my disease with diet, exercise, and meds. I use a blood sugar monitor daily. It will give you a good idea of what to eat and what to avoid. You will also be able to see the effects of exercise on your blood sugar levels. I have had no side effects from the disease, such as neuropathy or changes to blood vessels in my eyes. Recently my disease ticked up a notch. The things I had been doing did not control my levels as well as I liked. So, back to Weight Watchers and I had to get serious about walking and losing weight. It's a good sign that you are taking this seriously. You will be fine, and if you watch your diet, control your weight, and exercise regularly, you may never have to take any medication at all. Sorry for going on at some length, but when I was in your position, a co-worker who was diabetic took me firmly in hand. I owe him a lot. Just take charge. You can do it.