Prediabetes means your blood glucose (sugar) is higher than normal, but not yet diabetes. More than 1 in 3 American adults has prediabetes. Diabetes is a serious disease that can cause heart attack, stroke, blindness, kidney failure, or loss of feet or legs. The good news is that losing weight and being active can cut your risk of type 2 diabetes in half. The National Diabetes Prevention Program is designed to delay or prevent type 2 diabetes.