In 2000 and 2001, investigators at the University of Alberta, Edmonton reported that more than 3 out of 4 diabetic patients treated with islet transplantation under their protocol were able to discontinue insulin injections for up to 20 months. This success reignited the world's enthusiasm about islet transplantation as a potential, long-awaited cure for type 1 diabetes and hundreds of new islet transplant research programs were created internationally, including one at the City of Hope.
A five-year follow-up report published by the Edmonton group in 2005 indicated that only about 1 out of 10 subjects remained off insulin 5 years after transplant. However, most patients who had to restart insulin needed only a fraction of their pre-transplant dose and continued to enjoy other important, long-lasting benefits of their transplants, including elimination of dangerous low blood sugar episodes and overall improvement in blood sugar control.
Outcomes from the first City of Hope clinical islet transplantation trial are similar to those initially reported by Edmonton and other leading islet transplantation programs. Some more recent islet transplant studies have used stronger (T-cell depleting) immunosuppression medications than the ones used in the Edmonton study, such as anti-thymoglobulin (ATG).
According to the Collaborative Islet Transplant Registry, 5-6 out of every 10 patients who received T-cell depleting immunosuppression for their islet transplant remained off insulin five years after transplant, which is consistent with the long-term outcomes of whole pancreas transplant.