Randomized controlled trials (RCTs) involving patients with T1D receiving teplizumab in the intervention arm and placebo (or no active intervention) in the control arm were searched throughout the electronic databases. The primary outcome was the change in area under the curve (AUC) of C-peptide levels from baseline.

Seven reports from six studies involving 834 subjects met the inclusion criteria. Compared to teplizumab, greater reductions in AUC of C-peptide from the baseline values were observed in the control group after six months (MD 0.07 nmol/L [0.01, 0.13], P=0.02), after 12 months (MD 0.07 nmol/L [0.04, 0.11], P=0.0001), after 18 months (MD 0.10 nmol/L [0.06, 0.14], P<0.00001), and after 24 months (MD 0.07 nmol/L [0.01, 0.14], P=0.03) of interventions. Moreover, fewer patients treated with teplizumab had a decreased C-peptide response after six months (OR 0.21), after 12 months (OR 0.17), after 18 months (OR 0.30) and after 24 months (OR 0.12) of treatment. The preservation of endogenous insulin production was supported by reduced use of exogenous insulin with maintenance of comparable glycemic control for up to 18 months post-treatment. Teplizumab imparted higher risks of grade 3 or higher adverse events (AEs), AEs leading to study medication discontinuation, nausea, rash, and lymphopenia.