Insulin therapy for diabetes mellitus is based on diet and exercise therapy.People with type 1 diabetes mellitus have an absolute deficiency of insulin and require lifelong insulin therapy. For patients with type 2 diabetes, insulin treatment is also required if the following conditions occur, including the combination of severe acute complications or chronic complications of diabetes; to do major surgery, as well as pregnancy, breastfeeding diabetic patients; by a variety of oral hypoglycemic drug treatment effect is poor, accompanied by weight loss type 2 diabetic patients; difficult to classify the diabetic patients with emaciation, also need to use insulin treatment. Newly diagnosed patients with type 2 diabetes mellitus who are accompanied by significant hyperglycemia and glycated hemoglobin >9% also require short-term intensive insulin therapy. During insulin therapy, care should be taken to mimic the physiological insulin secretion pattern as much as possible, starting with a small dose and gradually adjusting the dose according to blood glucose to avoid hypoglycemia as much as possible.