Type 1 diabetes mellitus (T1DM) is an autoimmune disease in which insulin-secreting islet beta cells of the pancreas are destroyed by a type of white blood cell called a T cell. While most people with T1DM must receive insulin injections to maintain proper blood glucose levels, a recent option for some patients is to undergo islet transplantation, which replaces the insulin secreting cells they have lost with new donor cells. However, the immunosuppressive drugs required to prevent graft rejection are costly and have serious side effects. Researchers continue to search for new methods to achieve long term transplant survival. T regulatory (Treg) cells have great potential to protect islet grafts from rejection. Treg cells are a subset of white blood cells with the capacity to suppress immune responses. It has been shown that a key protein named FOXP3 is essential for the development and function of Treg cells. T cells expressing this protein can reduce autoimmune disease and reverse established diabetes in mice. Researchers recently developed a method for converting human T cells into Treg cells. Alicia McMurchy is generating human Treg cells and testing their ability to inhibit graft rejection in a mouse model. Her prediction is that the generated Treg cells will inhibit graft rejection and allow long-term survival of transplanted islets. If validated, this approach could indicate a promising future for clinical use of Treg cells in transplantation, potentially alleviating the need for expensive and harmful immunosuppressive drugs and improving the health and quality of life of T1DM patients and other transplant patients.