A simple change in diet prevents the development of core symptoms of type 2 diabetes, such as frequent urination and sudden weight loss.   And it became clear to researchers from Sweden that eating foods containing whole grains reduces the risk of developing type 2 diabetes, after following up on the health status of more than 55,000 people over many years.   The researchers point out that such research included only Americans, who were getting whole grain products based on wheat. And now scientists are starting to take an interest in other grains that contain dietary fiber and biologically active…