AIM: To investigate the expression of copeptin and midkine(MK)in patients with diabetic retinopathy and their clinical significance.

METHODS: Totally 180 patients with type 2 diabetes mellitus(T2DM)admitted to our hospital from June 2016 to October 2017 were divided into three groups according to the criteria of diabetic retinopathy staging. Among them, there were no retinopathy group(68 cases), non-proliferative retinopathy group(72 cases), proliferative retinopathy group(40 cases)and 90 healthy subjects in the same period as the control group. The copeptin level was detected by double antibody immunosorbent assay and the MK level by ELISA. The glycosylated hemoglobin(HbA1c)was detected by TOSOH automatic glycosylated hemoglobin analyzer and the whole blood hs-CRP was detected by using blood routine instrument. Fasting plasma glucose(FPG), triglyceride(TG), cholesterol(TC), low density lipoprotein(LDL-C)and high density lipoprotein(HDL-C)were detected by automatic biochemical analyzer and the systolic blood pressure(SBP)and diastolic blood pressure(DBP)of each group were recorded. The relationship between copeptin and MK levels and blood lipid, blood pressure, biochemical parameters and the course of diabetes mellitus were also analyzed.

RESULTS: The levels of copeptin and MK in patients with diabetic retinopathy were significantly higher than those in controls, and the levels of copeptin and MK were gradually increased with the progress of disease(P<0.05). The levels of copeptin and MK were correlated with the levels of HbA1c, hs-CRP and course of T2DM(P<0.05), but no significant correlation with plasma lipids, blood pressure and FPG(all P>0.05).

CONCLUSION: The copeptin and MK levels are closely related to the course of diabetic retinopathy and the severity of the disease, both of which may be involved in the development of diabetic retinopathy.