AIM: To investigate the efficacy of aflibercept combined with sub-tenon injection of triamcinolone acetonide (TA) in treating diabetic macular edema (DME) and to examine changes in growth factors and inflammatory mediator levels in aqueous humor after injection. METHODS: Totally 67 DME patients (67 eyes) and 30 cataract patients (32 eyes) were enrolled as the DME group and the control group, respectively. The DME group was divided into the aflibercept group (34 cases) and the aflibercept combined with TA group (combined group, 33 cases). The aqueous humor of both groups was collected during the study period. The aqueous levels of vascular endothelial growth factor (VEGF), monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-1β (IL-1β) were detected using a microsphere suspension array technology (Luminex 200TM). Aqueous cytokines, best-corrected visual acuity (BCVA), central macular thickness (CMT), and complications before and after treatment were compared between the aflibercept group and combined group. RESULTS: The concentrations of VEGF, MCP-1, IL-6, and IL-8 in the aqueous humor were significantly higher in the DME group than those of the control group (all P<0.01). After 1mo of surgery, the concentrations of VEGF, MCP-1, IL-6, and IL-8 in the aqueous humor were significantly lower in the combined group than those of the aflibercept group (all P<0.01). The BCVA and CMT values of the two groups were statistically different after 1 and 2mo of treatment (P<0.01). However, the difference was not statistically significant after 3mo of treatment (P>0.05). CONCLUSION: The cytokines VEGF, MCP-1, IL-6, and IL-8 in the aqueous humor of DME patients are significantly increased. Aflibercept and aflibercept combined with TA have good efficacy in DME patients, can effectively reduce CMT, improve the patient’s vision, and have high safety. Aflibercept combined with TA can quickly down-regulate the aqueous humor cytokines and help to relieve macular edema rapidly. However, the long-term efficacy is comparable to that of aflibercept alone.