Background: Diabetic retinopathy (DR) has emerged as a leading cause of visual impairment and blindness in the working-aged population worldwide. This study aimed to assess frequency and associated factors of progression of DR in subjects with known diabetes in a population-based setting.

Methods: The Beijing Eye Study is a population based study performed in Greater Beijing in 2001 and 2006. The present investigation included all subjects with known diabetes mellitus in 2001, who participated in the follow-up examination in 2006. Fundus photographs were assessed.

Results: The study included 170 subjects; 51 (30%) subjects showed signs of DR in 2001 and were re-examined in 2006, 36 (21.2%) subjects (18 subjects with DR present at baseline, 18 subjects with newly diagnosed DR in 2006) showed a progression of DR during follow-up. Progression of DR was associated with rural region (odds ratio (OR): 5.43, P = 0.001) and self-reported arterial hypertension (OR: 3.85, P = 0.023). In the non-progressive subgroup, presence of DR was associated with different levels of education (< middle school, middle school, college or higher, OR: 0.30, P = 0.023), treatment modes of diabetes mellitus (OR: 10.24, P = 0.003) and cataract surgery (OR: 9.14, P = 0.007).

Conclusions: In a population-based setting in Greater Beijing, progression of DR occurred in 35% of subjects with pre-existing DR and overall in 21% of subjects with known diabetes within a 5-year period. Progression of DR was significantly associated with rural region and self-reported arterial hypertension. In the stable subjects, presence of DR was significantly associated with poor educational level, insulin treatment of diabetes and cataract surgery.