AIM: To assess the inflammatory cytokines expression in aqueous humor in diabetic primary open angle glaucoma (POAG) patients. METHODS: A cross-sectional study on 87 eyes, distributed as following: 26 eyes from diabetic patients, 16 eyes with POAG and 21 eyes from diabetic POAG patients; healthy controls (24 eyes) were recruited from patients undergoing conventional cataract surgery. A volume of 100 μL of aqueous humor (AH) was collected during phacoemulsification and 21 inflammatory markers were quantified using a Luminex® cytometric bead assay: IL-1Ra, IL-1α, IL-1β, IL-5, IL-6, IL-10, IL-17, GM-CSF, IFNγ, CCL2, CCL3, CCL4, CXCL5, CXCL8, bFGF, VEGF, TNFα. Main changes in cytokine profile were analyzed and compared between groups. Data on demographics, duration of glaucoma, intraocular pressure (IOP), number of anti-glaucoma substances were recorded for correlation analysis and prediction models. RESULTS: Significant differences in cytokine expression between groups were detected for CXCL5 (P<0.001), CXCL8 (P=0.004), IL-1α (P<0.001), IL-2 (P<0.001), CCL4 (P=0.003), CCL5 (P<0.001) and TNFα (P=0.05). Post-hoc analysis identified IL-2 (P=0.009) and CXCL5 (P<0.001) as “separation markers” between POAG and diabetic POAG eyes. In POAG patients, the “separation markers” could highly predict the TNFα levels F(1, 16)=14.639, P<0.001, whereas in diabetic patients F(1, 24)=4.844, P=0.006 and diabetic POAG patients F(1, 19)=2.358, P=0.05 the level of prediction was inferior. CONCLUSION: Our results reveal an inflammatory model based on increased TNFα levels in POAG eyes. Simultaneous co-stimulatory molecules and additional inflammatory pathways need to be further explored in diabetic POAG cases, since the prediction model could only partially explain the increased TNFα level in this category of patients.