Diabetic macular edema (DME) is a common complication of diabetic retinopathy and is the leading cause of vision loss in diabetic patients. Various factors, such as metabolic disorders and inflammation caused by hyperglycemia, are involved in the occurrence and development of DME, but the specific mechanism is still unclear. Müller cells are a type of macroglial cell unique to the fundus, distributed throughout the retina, and they play a unique role in retinal homeostasis. This article reviews the role of Müller cells in the pathological process of DME and the research progress in the treatment of DME by targeting Müller cells through gene therapy.