As the number of diagnoses of diabetes mellitis continues to increase, so does the incidence of diabetic complications, such as gastroparesis. The current case report examines the effect of osteopathic manipulative treatment (OMT) on the symptoms of diabetic gastroparesis in a patient with type 1 diabetes mellitus. After a prescribed regimen of OMT, the patient’s Gastroparesis Cardinal Symptom Index score improved from 13 to 8, and his hospitalization stays decreased from once every 6 to 8 weeks to once in 6 months. After 6 sessions of OMT, the patient experienced a reduction in and subsequent relief of diabetic gastroparesis symptoms and improved quality of life. The role of OMT needs to be further investigated as a cost-effective adjunctive treatment for patients with diabetic gastroparesis.