Abstract: Diabetic retinopathy (DR) which is one of the common microvascular complications of diabetes mellitus is an important cause of vision impairment in diabetic patients. The pathogenesis of DR is not yet clear. As an important component of the immune system, complement system not only plays a key role in defending against exogenous microbial infestation, but also has a place in regulating the immune response and mediating inflammation. A large number of studies have demonstrated that the complement system are involved in the development of DR through classical pathway, the alternative pathway, the lectin pathway, and abnormal function of complement regulatory proteins, which will provide new ideas for studying the pathogenesis of DR as well as treatment options.(Int Rev Ophthalmol, 2022, 46: 477-480, cover III)

Key words: iabetic retinopathy/pathogenesis, complement system