| Outcome Measures: |
Primary: Number of participants with Stage 3 Type 1 Diabetes based on American Diabetes Association criteria, From baseline up to Week 104|Change from baseline in area under the curve (AUC) of C-peptide, From baseline up to Week 104|Change from baseline in endogenous insulin, From baseline up to Week 104|Number of participants with TEAEs, SAEs, AEs leading to permanent study intervention- or study discontinuation; AEs of special interest; number of participants with clinically significant changes in vital signs, ECG, and/or safety laboratory test, TEAE: treatment-emerged adverse event; SAE: serious adverse event; AE: adverse event, Throughout the study, approximately 756 days | Secondary: Change from baseline in fasting plasma glucose (FPG) from an oral glucose tolerance test, From baseline up to Week 104|Change from baseline in 2-hour plasma glucose from an oral glucose tolerance test, From baseline up to Week 104|Change from baseline of hemoglobin A1c (HbA1c), From baseline up to Week 104|Serum concentration of teplizumab, From Day 1 to Day 28|CD3 receptor occupancy, From baseline to Day 28|Number of participants with anti-drug antibodies, From baseline up to Week 104|Number of participants with neutralizing antibodies, From baseline up to Week 104
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