Abatacept improved immune cell subsets and insulin secretion in patients with T1DM, including reducing the frequency of inducible T‐cell costimulatory (ICOS)+ PD1+ Tfh cells, naive CD4+ T cells, and the frequency of CD4+ regulatory T cells (Tregs) upregualtion.250, 251. This evidence concerns the gene CD4 and type 1 diabetes mellitus.