AIM: To analyze the changes of serum homocysteine(Hcy), vitamin B12(VitB12)and folic acid in the serum of patients with diabetic retinopathy(DR), and to explore their significance in the occurrence and development of DR.

METHODS: A case-control study was designed. A total of 95 patients with DR(DR group), 94 patients with diabetes mellitus(DM group)treated in endgcrinology department and 87 patients with age-related cataract(normal control group)from the ophthalmology department of Shenzhen People's Hospital between July 2021 and January 2022 were selected. Fasting venous blood was collected and serum was separated. The concentration of Hcy in serum was detected by enzyme linked immunosorbent assay(ELISA), and chemiluminescence immunoassay was used to detect the concentration of VitB12 and folic acid. Pearson linear correlation analysis was used to evaluate the correlation between Hcy and clinical parameters. Multivariate linear regression analysis was used to evaluate the main factors which affect Hcy level. Receiver operating characteristic(ROC)curve was designed to analyze the diagnostic value of serum Hcy, VitB12 and folic acid in DR.

RESULTS: The concentration of serum Hcy in DR group was 16.52±3.54 μmol/L, which was significantly higher than that in DM group(10.86±3.47 μmol/L)and control group(6.84±1.39 μmol/L; all P<0.05); The concentration of VitB12 in the serum of the control group was 501.79±108.95 pmol/L, which was higher than that in DM group(478.57±57.85 pmol/L)and DR group(455.88±181.49 pmol/L), but the difference was not statistically significant(P=0.054); The concentration of folic acid in serum of control group was 10.31±2.43 nmol/L, which was higher than that of DM group(9.94±1.90 nmol/L)and DR group(7.27±2.79 nmol/L), and the difference between DR group and DM group was statistically significant(P<0.05); In DR group, Hcy expression was weakly positively correlated with triglyceride and low density lipoprotein(r=0.208, P=0.043; r=0.240, P=0.019). Multivariate linear regression showed that low density lipoprotein was an important factor which affect the expression of Hcy in DR patients. ROC curve shows that Hcy has important value in the diagnosis of DR.

CONCLUSIONS: Hcy, VitB12 and folic acid are differentially expressed in DR group, DM group and normal control group. Hcy may be involved in the pathogenesis of DR, and it has important value in the diagnosis of DR. In addition, low density lipoprotein is also an important factor which affects the expression of Hcy.