Insulin is an important drug for the treatment of diabetes mellitus with the following indications: 1. Patients with type 1 diabetes mellitus must use insulin; 2. Patients with diabetes mellitus during pregnancy need to use insulin; 3. Newly diagnosed patients with high blood glucose and young patients need intensive insulin treatment; 4. Patients with type 2 diabetes mellitus have acute infections and stressful situations that lead to a short period of elevated blood glucose and need to use insulin to control blood glucose; 5. Some Diabetic patients with serious complications and large side effects of oral hypoglycemic drugs need to be treated with insulin. 6. Patients with obvious abnormalities in liver and kidney function and contraindications to oral drugs.