Guangzhou Diabetic Eye Study: rationale, design, methodology and baseline data

Purpose: The incidence and risk factors for diabetic retinopathy (DR) in southern China remains unclear. This project aims to explore the onset and progression of DR and their determinants through a prospective cohort in South China. Methods: The Guangzhou Diabetic Eye Study (GDES) recruited patients with type 2 diabetic patients registered in the community health centres in Guangzhou, China. Patients with history of ocular treatment, severe refractive opacity, or other systemic diseases were excluded. Comprehensive examinations were performed including visual acuity, refraction, ocular biometry, fundus imaging, blood and urine tests. The biological samples were collected for further study. Results: A total of 2305 eligible patients were included in the final analysis. In total, 14.58% of the participants had any DR and 4.25% had vision-threatening DR (VTDR), among which 76 (3.30%), 197 (8.55%), 45 (1.95%) and 17 (0.74%) were classified as mild NPDR, moderate NPDR, severe NPDR and PDR, respectively. There were 93 (4.03%) patients of diabetic macular edema (DME). The presence of any DR was independently associated with a longer duration of DM, higher degree of HbA1C, insulin treatment, higher average arterial pressure, higher concentration of serum creatinine, presence of urinary microalbumin, older age, and lower BMI (all P <0.001). For VTDR, 7 factors were significant: older age, a longer duration of DM, higher concentration of HbA1c, use of insulin, lower BMI, higher concentration of serum creatinine, and high albuminuria (all P<0.05). These factors were also independently associated with DME (all P <0.001). Conclusions: The GDES is the first large-scale prospective cohort study of the diabetic population in southern urban China, which will help to identify newer imaging and genetic biomarkers for DR in this population.