Plasma and vitreous selenium concentrations in patients with type 2 diabetes and diabetic retinopathy

Background: This work aimed to determine and compare plasma and vitreous selenium (Se) concentrations in patients with type 2 diabetes and diabetic retinopathy (DR). Methods: A total of 60 type-2-diabetes patients including 20 without DR, 20 with non-proliferative DR (NPDR), and 20 with proliferative diabetic retinopathy (PDR), were involved in this study. Blood plasma samples were collected from above 60 patients and 20 normal controls (without diabetes). Twenty control vitreous samples were obtained from the eyes presenting a macular hole and epimacular membrane. Vitreous samples were also collected from PDR patients receiving one-week intravitreal anti-VEGF therapy or not. Plasma and vitreous Se concentrations were determined by inductively coupled plasma mass spectrometry. Results: Plasma Se concentrations in PDR patients (163.74 +/- 32.68 mu g/L) were significantly higher than those in normal control patients (121.59 +/- 28.33 mu g/L), NPDR patients (130.34 +/- 29.11 mu g/L), and the patients without DR (81.23 +/- 20.59 mu g/L) (all P < .001). Similarly, Se concentrations in vitreous samples of PDR patients (56.30 +/- 12.03 mu g/L) were consistently higher than those in control vitreous samples (26.26 +/- 6.53 mu g/L). In addition, vitreous Se concentrations in PDR patients decreased to 47.76 +/- 9.72 mu g/L after intravitreal injection of the anti-VEGF drug ranibizumab for one week, which was significantly lower than those before injection (P = .02). Plasma VEGF levels of diabetic patients were lower than those of the normal controls (P < .001). On the contrary, the vitreous VEGF level in the PDR group (913.61 +/- 193.32 pg/mL) was significantly higher than that of the normal control group (101.23 +/- 21.33 pg/mL) (P < .001). Conclusion: The elevation of Se concentrations may be an important risk factor in plasma and vitreous with diabetic retinopathy among type-2-diabetes patients. The elevated VEGF may be also closely related to the intraocular Se concentration in PDR patients.