We identified 4 inflammatory factors causally associated with GBM risk: CCL25 (OR = 1.24, 95% CI = 1.02–1.51), M-CSF1 (OR = 1.70, 95% CI = 1.09–2.68), and IL-33 (OR = 1.61, 95% CI = 1.01–2.56) showed risk-increasing effects, while FGF21 (OR = 0.57, 95% CI = 0.37–0.89) demonstrated protective effects. Here, FGF21 is linked to glioblastoma.