High blood sugar can also be due to a lack of chromium in the diet.
Some people do not buy expensive "gluten-free" processed foods, but rather, simply eat meats, fruits and vegetables, and some grains such as brown and wild rice and quinoa. In other words, just avoid processed foods and wheat, rye, barley (and for now, oats). Read up on this at http://www.theglutenfile.com

Good for you for trying to get to the bottom of what truly ails you. Oh, and do not forget gut health such as probiotics.