In terms of prevention, an abatacept clinical study was conducted on 81 stage 1 T1D patients (abatacept: 35 patients, placebo: 46 patients), where the disease progression was not significantly delayed, but abatacept reduced PD-1+ T-follicular helper (Tfh) cells (P < .0001), increased naive CD4+ T cells, and also reduced the frequency of Tregs from the baseline (P = .0067), with complete return to baseline in 1 year after treatment. The gene discussed is PDCD1; the disease is type 1 diabetes mellitus.