This study is for people who were part of a previous type 1 diabetes study and have now been diagnosed with type 1 diabetes. Participants will receive a medication called teplizumab through an IV (a tube that goes into your vein) for 12 days. The study will last for about 78 weeks (a little over a year and a half) to check if the treatment is safe and how it affects the body.

Key Points:

• Duration: 78 weeks with a 12-day treatment period.
• Only one treatment group, no comparison groups.
• Participants must start treatment within one year of their type 1 diabetes diagnosis.

To join, you must have been in the earlier study, been diagnosed with type 1 diabetes, and you can't try other experimental treatments during this study. You can't join if you have an active infection, certain viruses like HIV or hepatitis, or any condition that could affect your safety in the study. It's important to talk with your guardian and get their permission if needed.