Plasma level of interleukin-6 is an indicator for predicting diabetic macular edema.

PURPOSE To find a predictor in the pathogenesis of macular edema, we investigated ocular and systemic risk factors. METHODS One hundred and fifty-nine patients with mild diabetic retinopathy who showed one or more soft exudates were recruited. We selected the possible predictors on the basis of relevant factors, including concentration of vascular endothelial growth factor, interleukin-6 (IL-6), transforming growth factor (TGF)-beta(1), tumor necrosis factor (TNF)-alpha, and lipoprotein(a) in plasma, and serum level of von Willebrand factor and thrombomodulin. RESULTS Macular edema was not detected in 94 eyes; focal macular edema was detected in 46 eyes; diffuse macular edema was detected in 18 eyes; and cystoid macular edema was present in 1 eye. The plasma level of IL-6 concentration and the state of the posterior vitreous detachment (PVD) correlated significantly with the severity of macular edema (odds ratios = 3.68, 1.70, respectively). Other risk factors were not significantly associated with macular edema. We estimated the probability of macular edema according to the IL-6 level in plasma and the state of the PVD, and were able to predict the probability of macular edema. CONCLUSION The results of the present study indicate that IL-6 concentration in plasma and the state of the PVD can be predictors of macular edema.