Long-term insulin administration is a therapeutic measure to control blood glucose and does not affect the patient’s life expectancy. The life expectancy of a diabetic patient is related to whether the blood glucose control is up to standard and whether the control of complications is satisfactory. Insulin in the body is secreted from pancreatic B cells in the pancreas and mainly promotes the storage of glycogen in target tissues such as liver, fat and muscle. One part is basal insulin secretion that is not dependent on eating, and the other part is massive insulin secretion caused by hyperglycemic stimulation after eating. Diabetes mellitus can result from inadequate insulin secretion and/or impaired bioavailability of insulin in the body. Insulin is a commonly used clinical drug for the treatment of diabetes mellitus and one of the most effective measures for lowering glucose. Poor glycemic control in diabetic patients can lead to a variety of complications, such as diabetic nephropathy, retinopathy, vasculopathy, diabetic foot, and infections. These common complications of diabetes are the main factors affecting the life expectancy of diabetic patients. The length of life of diabetic patients is not related to whether or not they take insulin for a long period of time, but is related to the level of blood glucose control and the severity of complications. Standardized treatment under the guidance of a doctor to control blood glucose within a reasonable range can reduce the risk of microvascular and macrovascular lesions in diabetic patients, improve the quality of life and extend life expectancy.