The disclosure provides methods for treating diabetes by promoting graft survival and improved graft function in a patient receiving an islet transplant by treating the patient with a GLP-1 receptor agonist compound prior to the islet transplant. The methods may also comprise treating the islets with a GLP-1 receptor agonist compound prior to transplanting them in a patient. The methods may eliminate the need for immunosuppressive therapy in islet transplants. Any GLP-1 receptor agonist compound know in the art can be used in the methods described herein.