Our study aimed to detect the expression of OX40/OX40L and Tfh cells in the peripheral blood of patients with T1DM and explore the potential mechanisms of Tfh and B cell differentiation regulated by OX40/OX40L signaling in T1DM, which could provide potential therapeutic targets for developing novel therapies for T1DM. Here, TNFSF4 is linked to type 1 diabetes mellitus.