Insulin can be used in combination with selegiline with dietary control and exercise, and the two can be used together for better control of blood glucose levels. Sitagliptin, together with diet and exercise, can be used to improve glycemic control in patients with type 2 diabetes who have poor glycemic control after insulin monotherapy. It is important to control the dosage of the drug to prevent hypoglycemia due to overdose, and the drug needs to be adjusted under the guidance of the clinician. The common adverse reactions of selegiline include allergy, elevated liver enzymes, upper respiratory tract infection, pancreatitis, etc.; the common adverse reactions of insulin are hypoglycemic reaction, allergic reaction, edema, weight gain, refractive error, etc.. It is contraindicated in patients who are allergic to any component of the drug. Drug adjustments should be made strictly under the guidance of the clinician, and should not be self-administered.