There is NO Book I would recommend off hand. As a Diabetic myself, the first thing to do would be lose 1%-12% body weight right off. Also stay away from Carbohydrates (Rice, Potatoes, Bread, Cereals, etc, and of course sweets if all possible). Exercise is a major preventive of Diabetes
. Even if it's just walking 15 minutes 3-4 times a week can make a big difference.
It wouldn't hurt to have her blood sugar checked with a Glucometer fairly often just to see what her blood sugar looks like before breakfast, 1 hour after breakfast, and, again later. The test strips can be expensive so hopefully she has Insurance or Medicare or Medicaid. I learned I probably had Diabetes for about 4_ years before I was diagnosed. This disease is a Monster, and, attacks everyone different. I'd suggest she make life changes now, before she has a problem. The preventive measures are far more easy to deal with than once one gets Diabetes, The damage it can do to the Heart, Kidneys, Legs, Feet, Circulation, and lead to Strokes & Heart attacks does not compare to the preventive measures being a pain in the butt or one saying: "I can't do it" is Baloney! It sure beats having a stroke, or your feet and.or legs amputated later. Betterr to take control now than the Diabetes take control later, at which point, it will run your life, and, make it miserable. Now I have to take Insulin
everyday. It's up to me if I want to turn things around or die a miserable death. I hope you stand up and fight before fighting is not an option.