Objective To describe the prevalence and severity of diabetic retinopathy (DR) and sight-threatening DR (STDR) among Chinese adults with diabetes.

Design, setting and participants A cross-sectional epidemiological survey across Mainland China (N=13 473). Participants were diagnosed with diabetes mellitus by physicians and transferred to our screening clinics (1/3 from hospital patients, 1/3 from city residents, the other 1/3 from rural residents). 2 fundus photographs were taken of each eye with a colourful, non-mydriatic and non-stereoscopic camera and were graded according to the UK guidelines.

Main outcomes and measures The prevalence and severity of DR and STDR.

Results Of the 13 473 participants with diabetes participating in the study, 4591 had DR and 1769 had STDR, for an overall prevalence of 34.08% (95% CI 33.28% to 34.88%) and 13.13% (95% CI 12.56% to 13.70%), respectively. Among these, gradable photographs were available for 12 780 participants (94.86%). Participants who were aged >65 years were less likely to suffer from DR or STDR (p<0.001; age distribution). No gender-related differences were present (p>0.05). Participants with STDR suffered from more severe visual impairment compared with those without STDR (p<0.001). The prevalence of DR and STDR in the northern region was higher than in the southern region (p<0.001). The prevalence of DR was closely related to duration of disease (OR 2.63; 95% CI 2.42 to 2.86; p<0.001) and diabetes onset age (OR 0.38; 95% CI 0.35 to 0.41; p<0.001).

Conclusions The prevalence of DR and STDR in Mainland China appeared a little high, and varied according to area. Non-proliferative DR was more common, but STDR needed prompt treatment, especially in economically less developed areas. This study highlights the necessity for DR screening and treatment in Mainland China.