Diabetes mellitus is a leading cause of morbidity and mortality in the Western world. Currently, the only forms of β-cell replacement are whole organ pancreas transplantation and pancreatic islet transplantation. Whole organ transplantation has demonstrated benefits in prevention and reversal of diabetic complications with sustainable long-term outcomes. Pancreatic islet transplantation continues to be a field that needs further study to ascertain the true benefit of islet transplantation for diabetic complications. This can only be achieved with improvement in long-term islet allograft survival.