Additional Study Information: The purpose of this study is to learn if the use of two drugs, Rituximab and Abatacept, one after the other, will help to extend insulin production in people newly diagnosed with type 1 diabetes (T1D). These two medications may potentially help each other with altering the immune response that causes the attack on insulin-secreting cells in the pancreas. T1D RELAY will study if two treatments consecutively performs better than Rituximab alone. Researchers will test if those who are also treated with Abatacepthave better C-peptide levels over time.