Diabetic macular edema (DME) is a common complication of diabetes that can lead to severely impaired visual acuity.Its pathogenesis is complex, which is closely related to the destruction of blood-retinal barrier, and there are many cytokines involved in its formation, but the exact mechanism is not yet fully clear.Recent researches suggested that some typical pathological characterizations of retina can be used as criteria for evaluating its occurrence, and it is known that a variety of risk factors participated in the pathological process, such as glucose, blood pressure, blood lipids, which are well-known and can be closely correlated with its development through impacting the systemic and retinal vascular functions by complex mechanisms and leading to endothelial dysfunction.While other systemic risk factors, such as diabetic nephropathy which leads to changes in osmotic balance, anemia which increases cytokines caused by ischemia and hypoxia, excessive body weight which leads to vascular damage through fat factor, smoking that produces blood vessel damage by promoting oxidative stress on the body and various hypoglycemic drugs, will influence the development of macular edema on different levels.So conducting a comprehensive and newest understanding of this disease and its risk factors are conducive to better prevention efforts for diabetes patients.This review mainly summarizes the latest researches on definition, classification, pathologic characterization and risk factors of DME.

Diabetes; Diabetic retinopathy; Diabetic macular edema; Risk factors