When it comes to preventing diabetes, your diet can make a big difference. And if you already have it, a diet change may help you manage it better.The right mix of foods keeps your insulin and blood sugar in check. When you have insulin resistance, that balance gets out of whack. It's harder for your body to burn foods for energy. And when too much sugar builds up in your bloodstream, you may be on the path to type 2 prediabetes or diabetes.And that...