Increased serum chemerin levels in diabetic retinopathy of type 2 diabetic patients

Purpose: To compare serum levels of chemerin in type 2 diabetes mellitus (T2DM) with or without retinopathy, and to investigate the relationship between serum chemerin levels and diabetes retinopathy.Materials and methods: A total of 60 T2DM patients and 20 healthy subjects (control group) were enrolled in this study. Of the T2DM patients, 15 had proliferative diabetic retinopathy (PDR group), 20 had non-proliferative retinopathy (NPDR group) and 25 had no retinopathy (T2DM group). Their serum samples were collected for testing the levels of chemerin, vascular endothelial growth factor (VEGF), C-reactive protein (CRP) and so on. The values were analyzed to compare the differences among the groups. Simple linear regression analysis and multiple stepwise linear regression analysis were used to determine the correlations between variables and chemerin. Trend chi-square was used to determine the correlations between chemerin and the severity of diabetic retinopathy (DR).Results: Chemerin levels in group PDR, NPDR and no DR were 147.56 ± 35.98 g/l, 128.09 ± 16.33 g/l and 113.19 ± 19.89 g/l, with the significant difference across the three groups (p < 0.05). But there was no difference between control group (109.55 ± 20.98 g/l) and T2DM group. Simple linear regression show that serum chemerin was correlated with duration of diabetes, body mass index (BMI), serum triglycerides, total-cholesterol, CRP and VEGF, and not correlated with age, systolic and diastolic blood pressure in T2DM patients. Stepwise regression analysis showed that BMI, CRP and VEGF were significantly associated with serum chemerin (p = 0.006, p = 0.011 and p = 0.036, respectively). In addition, the more severity of DR as the chemerin levels increased (χ² = 16.07, p < 0.001).Conclusions: Serum levels of chemerin were significantly increased in the NPDR and PDR group. Elevated serum level of chemerin and its positive correlation with BMI, CRP and VEGF suggested that chemerin was associated with obesity, inflammation and neovascularization and might be involved in the development of DR.