Type 2 diabetes mellitus, the most common form of diabetes, interferes with the body's ability to store foods, resulting in high blood levels of sugar. Over time, high blood sugar levels lead to complications such as blindness, kidney failure, and heart disease. Being overweight and physically inactive increases a person's chances of developing type 2 diabetes. Diet probably affects the risk for this disease, but it is difficult to separate the risk of diet from the risks of being overweight and inactive. Moreover, previous studies of diet and diabetes have given a narrow view of diet and diabetes because these studies focused on individual food components instead of the balance between different types of foods (dietary patterns).