OBJECTIVE To investigate the relationship between insulin resistance (IR)/β-cell dysfunction and diabetic retinopathy (DR) in Chinese patients with type 2 diabetes mellitus (T2DM), and to explore further whether there were differences in the relationship among diabetic patients with higher and lower body mass index (BMI). METHODS Cross-sectional study. A total of 1466 subjects with T2DM were recruited in a local Desheng Community of urban Beijing from November 2009 to June 2012 for the cohort of Beijing Desheng Diabetic Eye Study. Standardized evaluation was carried out for each participant, including questionnaire, ocular and anthropometric examinations, and laboratory tests. Seven fields 30° color fundus photographs were used for DR grading according to the Early Treatment Diabetic Retinopathy Study protocols. Homeostatis Model Assessment (HOMA) method was employed for IR and β-cell function assessment. RESULTS After excluding those participants who were treated with insulin (n=352) or had missing data of fasting insulin (n=96), and further excluding those with poor quality of retinal photographs (n=10), a total of 1008 subjects were included for the final analysis, 406 (40.3%) were men and 602 (59.7%) were women, age ranging from 34 to 86 (64.87±8.28)y. Any DR (levels 14 and above) was present in 278 (27.6%) subjects. After adjusting for possible covariates, the presence of any DR did not correlate with HOMA IR [odds ratio (OR) 1.51, 95% confidence interval (CI) 0.87-2.61, P=0.14] or HOMA β-cell (OR 0.71, 95%CI 0.40-1.26, P=0.25). After stratification by BMI, the presence of any DR was associated positively with HOMA IR (OR 2.46, 95%CI: 1.18-5.12, P=0.016), and negatively with HOMA β-cell (OR 0.40, 95%CI: 0.19-0.87, P=0.021) in the group of patients with higher BMI (≥25 kg/m2). In the group of patients with lower BMI (<25 kg/m2), the presence of any DR was not associated with HOMA IR (OR 1.00, 95%CI: 0.43-2.33, P=1.00) or HOMA β-cell (OR 1.41, 95%CI: 0.60-3.32, P=0.43). CONCLUSIONS The data suggest that higher IR and lower β-cell function are associated with the presence of DR in the subgroup of diabetic patients with higher BMI. However, this association is not statistically significant in diabetic patients with lower BMI.