Preserving β-cell function remains a key therapeutic goal after type 1 diabetes mellitus (T1DM) diagnosis. A systematic review and meta-analysis published in Diabetes, Obesity and Metabolism evaluated the efficacy and safety of T cell-targeted immunotherapy compared with placebo in newly diagnosed T1DM.

The analysis included randomized controlled trials identified through PubMed, Embase, CENTRAL, Web of Science, Scopus, and ClinicalTrials.gov through March 6, 2026. Overall, 21 trials involving 1,970 participants met the inclusion criteria. The primary outcome was change in C-peptide area under the curve (AUC).

Compared with placebo, T cell-targeted immunotherapy significantly increased C-peptide AUC at 6 months (SMD, 0.38; 95% CI, 0.19–0.57; p<0.001), 12 months (SMD, 0.41; 95% CI, 0.12–0.69; p=0.005), 18 months (SMD, 0.48; 95% CI, 0.32–0.65; p<0.001), and 24 months (SMD, 0.49; 95% CI, 0.32–0.65; p<0.001).

HbA1c levels and daily insulin dose also decreased at all time points (all p<0.05). Greater early-phase efficacy was observed in subgroups aged <18 years, those with worse baseline metabolic status, and trials with single-blind or open-label designs.

Total and serious adverse event risks were comparable between intervention and control groups. The findings indicate that T cell-targeted immunotherapy was associated with sustained β-cell function preservation and improved glycemic measures for at least 24 months in newly diagnosed T1DM.