Insulin aspart is used with a proper diet and exercise program to control high blood sugar in people with diabetes. Controlling high blood sugar helps prevent kidney damage, blindness, nerve problems, loss of limbs, and sexual function problems. Proper control of diabetes may also lessen your risk of a heart attack or stroke. Insulin aspart is a man-made product that is similar to human insulin. It replaces the insulin that your body would normally make. Insulin aspart starts working faster and lasts for a shorter time than regular insulin. It works by helping blood sugar (glucose) get into cells so your body can use it for energy. This medication is usually used with a medium- or long-acting insulin product.