Insulin lispro protamine/insulin lispro is used along with a proper diet and exercise program to control high blood sugar. It is used in people with type 1 (insulin-dependent) or type 2 (non-insulin-dependent) diabetes. This product is a combination of two man-made insulins: intermediate-acting insulin lispro protamine and rapid-acting insulin lispro. This combination starts working faster and lasts for a longer time than regular insulin.Insulin is a natural substance that allows the body to properly use sugar from the diet. It replaces the insulin that your body no longer produces, thereby lowering your blood sugar. 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.