Angiogenic eye disease is one of the most common causes of blindness. As IL-12 is known as quite strong anti-angiogenic factor, free IL-12 subunit: p40 is IL-12 antagonist and we aimed to determined its concentration and correlation with angiogenesis induced by sera of diabetic patients. We showed positive correlation between angiogenic activity of DM2 sera and their IL12p40 content. The mean number of newly formed blood vessels was significantly higher in DM2 patients as compared to control subjects. There were no differences between angiogenic activity in DM2 patients with and without retinopathy. Similarly we evaluated higher concentration of IL-12p40 in DM2 patients as compared to control group. No differences between patients with and without retinopathy were detected in IL-12p40 sera concentration. In case of DM1 patients angiogenic activity was lower as compared to healthy control patients, but IL-12p40 level was not different from the control.