Abstract: Retinal Müller cells are important glial cells in the retina. Müller cells provide neurons with trophic substances and remove metabolic wastes. They play a critical role in regulating the ion and water homeostasis of extracellular space and help to maintain the inner bloodretinal barrier. Most studies reported that Müller cells are closely associated with many retinal diseases, especially in the development of DR. Before the vascular lesions of diabetic retinopathy happen, Müller cells can affect retinal neural cells and retinal blood vessels by producing a variety of cytokines and taking part in the procedure of endoplasmic reticulum stress and oxidative stress. Müller cells have both protective and toxic effects on retinal neurons and were involved in the formation of diabetic macular edema.  (Int Rev Ophthalmol, 2014, 38:   395-399)