AIM:To investigate the role of serum high-sensitivity C-reactive protein(hsCRP)in the pathogenesis and progression of diabetic retinopathy(DR)in patients with type 2 diabetes mellitus(T2DM).METHODS:A nested case-control study was conducted involving 187 T2DM patients(187 eyes)who attended at Eye Center, Beijing Tongren Hospital, Capital Medical University from June 2017 to October 2024. Patients were categorized into three groups: the diabetes mellitus(DM)group, non-proliferative DR(NPDR)group, and proliferative DR(PDR)group. Baseline information was collected, including age, sex, duration of DM, and duration of hypertension. All patients underwent fasting biochemical tests and comprehensive ophthalmic examinations.RESULTS: A positive correlation was observed between hsCRP and fasting blood glucose(FBG; P=0.004)and glycated hemoglobin A1c(HbA1c; P=0.048)by Spearman's rank correlation coefficient analysis. After adjusting for confounding factors, multivariable Logistic regression identified hsCRP as a significant risk factor for DR(OR=2.67, 95% CI: 1.19-5.96, P=0.017). CONCLUSION:Serum hsCRP is positively correlated with FBG and HbA1c and can serve as an important predictor of the severity of DR.