Data collected by the United Network for Organ Sharing from all approved United States transplant programs were analyzed; the data included 20,290 adult diabetic patients who received primary pancreas transplants between October 1987 and December 2014. Simultaneous pancreas-kidney (SPK) transplantation has become the major therapeutic option for diabetes patients. The number of SPKs per year has not increased since 1999; it leveled off or decreased slightly each year. Recipients in the most recent period, 2010-2014, were more likely than recipients in any of the other periods to be non-white, older, male, to have had diabetes longer, to have higher body mass indices; and in this group there were more donor-recipient human leukocyte antigen mismatches. Donors in the 2010-2014 period were more likely to be younger and male and less likely to be white. Pancreas graft survival rates were highest in the 2010-2014 period (one-year graft survival 89.7%) vs. those for 1987-1989 (74.6%), 1990-1994 (77.5%), 1995-1999 (82.9%), 2000-2004 (84.4%), and 2005-2009 (85.5%); the five-year rates were 72.7% for 2010-14 vs. 60.0%, 64.3%, 69.0%, 70.9%, and 73.9% for the other periods, respectively. There was no decreased risk of graft failure for recent-era transplants compared with those of 1987–1989, except for those in 2005-2009. By year of transplant, the adjusted hazard ratios [with 95% confidence intervals (CI)] for overall loss of grafts surviving over one year in eras 1990–1994, 1995–1999, 2000–2004, 2005–2009, and 2010-2014 were, respectively, 0.85 (CI 0.66-1.09), 0.85 (CI 0.66-1.09), 0.87 (CI 0.67-1.13), 0.71 (CI 0.54-0.93), and 0.86 (CI 0.64–1.15). Chronic rejection caused 44.9% of graft losses between one and five years and 51.5% after five years. There is a need for a means to identify early markers of chronic rejection—and to control it—to improve long-term survival.