Simultaneous pancreas and kidney transplantation (SPK) is an accepted treatment for diabetic patients with renal failure, and is associated with increased survival and quality of life for recipients. There are only a few publications on the outcomes of simultaneous pancreas–kidney retransplantation (Re-SPK) after previous SPK and the loss of function of both grafts. A total of 55 patients with type 1 diabetes mellitus underwent pancreas retransplantation at our center between January 1994 and March 2021. Twenty-four of these patients underwent Re-SPK after a previous SPK. All 24 operations were technically feasible. Patient survival rate after 3 months, 1 year, and 5 years was 79.2%, 75%, and 66.7%, respectively. The causes of death were septic arterial hemorrhage (n = 3), septic multiorgan failure (n = 2), and was unknown in one patient. Pancreas and kidney graft function after 3 months, 1 year, and 5 years were 70.8% and 66.7%, 66.7% and 62.5%, and 45.8% and 54.2%, respectively. Relaparotomy was performed in 13 out of 24 (54.2%) patients. The results of our study show that Re-SPK, after previously performed SPK, is a technical and immunological challenge, associated with a significantly increased mortality and complication rate; therefore, the indication for Re-SPK should be very strict. Careful preoperative diagnosis is indispensable