Insulin is an effective method for diabetic patients to control blood glucose. There are many kinds of insulin, according to the time of action, there are short-acting insulin, intermediate-acting insulin, long-acting insulin, as well as insulin analogs and premixed insulin and so on. Novolin 50R insulin belongs to premixed insulin, which is made by mixing a certain amount of short-acting insulin and intermediate-acting insulin, containing 50% short-acting insulin and 50% intermediate-acting insulin in advance by the manufacturer for clinical convenience. Novolin 50R is injected subcutaneously before breakfast and dinner to effectively control both fasting blood glucose and postprandial blood glucose of the corresponding meal. Novolin 50R is suitable for patients with type 2 diabetes mellitus whose pancreatic β-cells still have some function. Novolin 50R insulin can be used alone or in combination with oral hypoglycemic agents such as biguanide hypoglycemic agents, glucosidase inhibitors, and insulin sensitizers.