Through this study, the investigators hope to understand the prevalence and influencing factors of diabetic retinopathy in Tianjin, improve the ability of complication detection and intervention in diabetic patients in primary medical and health institutions, and build a diabetes prevention and treatment network. The investigators should adhere to the policy of prevention first, combined with prevention and control, and explore a diabetes' prevention and control model suitable for our city. Extensive publicity and education should be carried out to improve the awareness of self-management ，improve the screening rate of diabetic retinopathy, and reduce the blindness rate.