Patients with type 2 diabetes who have indications for using metformin and selegiline and have no contraindications can take them together under the guidance of a doctor. Metformin can reduce hepatic glucose production, reduce intestinal absorption of glucose and increase insulin sensitivity and play a hypoglycemic effect. Sitagliptin can inhibit dipeptidyl peptidase-4, resulting in prolonged levels of active enteroglucagon, which regulates glucose homeostasis by promoting insulin synthesis and release and reducing glucagon secretion. It can be seen that metformin and selegiline are two different mechanisms of action of glucose-lowering drugs, for type 2 diabetes mellitus obese patients with insulin resistance, if there is no obvious contraindications such as liver, kidney, cardiorespiratory function, pancreatitis and so on can be combined medication, combined medication should pay attention to monitoring blood glucose, to avoid the occurrence of hypoglycemia; if the occurrence of heart attack, sweating, suggesting that there may be a hypoglycemia attack. It is recommended to take the above two drugs under the guidance of a doctor.