To evaluate the usefulness of cytokine levels of peripheral blood in diabetic retinopathy (DR), demographic and biochemical parameters including low-density lipoprotein (LDL) diameter as well as cytokine profiles were analyzed in 74 patients with type 2 diabetes mellitus (DM), with DR (n=46) or without DR (n=28). DM duration was longer in the patients with DR than without (p<0.001). Serum glucose (p=0.005) and total cholesterol (p=0.029) levels were higher in DM patients with DR than DM patients without DR. Plasma LDL diameter, interleukin-6 (IL-6), and interleukin-8 (IL-8) showed significant differences among the different degrees of DR severity in analysis of variance (ANOVA) with no definite trend. The risk of DR in DM patients was decreased by an increase of interleukin-10 (IL-10) level [odds ratio (OR)=0.152; confidence interval (CI): 0.028-0.817]. Plasma LDL diameter was smaller and IL-6 and tumor necrosis factor-alpha (TNF-alpha) levels were higher in DM patients with proliferative diabetic retinopathy (PDR) compared to those with non-proliferative diabetic retinopathy (NPDR) (p<0.05). We found that higher IL-10 levels were related to lower risk of DR in DM patients. Levels of IL-6 and TNF-alpha as well as LDL diameter may be helpful in the prediction of PDR in DM patients with DR.