Pancreas (PAK) or islet-after-kidney (IAK) transplantation are treatment options in patients with complicated type 1 diabetes (T1D) and a previous kidney transplantation in order to stabilize glycaemic control and/or delay (further) complications. We compared the middle and long term outcomes of PAK and IAK.

Methods: All subjects with T1D who had received a PAK or IAK at the LUMC between 2004-2018 were analysed. Inclusion criteria included a previous kidney transplantation, and follow-up duration of at least one year. The primary outcome was allograft function as defined by the Igls classification: 1) optimal, 2) good, and 3) poor graft function, or 4) graft failure. Treatment success was defined as optimal or good beta cell function.

Results: 31 PAK (17M/14F) and 29 IAK (19M/10F) recipients with a follow-up duration of 5.4±3.2 years were included. Before transplantation PAK recipients were younger than IAK recipients (42.1±5.2 versus 51.9±10.3 years, p<0.001), had a better kidney graft function (eGFR 52.0±10.1 versus 45.7±13.1 mL/min/1.73m², p=0.04) and similar HbA1c (68.5±21 versus 64±12.8 mmol/mol, p=0.33).

Treatment success rate in PAK and IAK respectively was 68% versus 72% at one year, 63% versus 69% at four years, and 60% versus 57% at seven years (p>0.7). At one year, insulin independence was higher in PAK than IAK (65% versus 28%, p=0.004) but also complete graft failure (CGF) was higher in PAK (29% versus 10%)(p<0.001). The same trend was noted at subsequent time points. At seven years, HbA1c had decreased to 46.0±12.9 (PAK; p=0.002) and 51.1±13.3 mmol/mol (IAK; p=0.05). Kidney graft function in PAK declined to an eGFR of 30.6 mL/min/1.73m² at 7 years (p=0.001). In IAK, a non-significant decline to 29.0 mL/min/1.73m² was observed (p=0.12). Total mortality was 19.4% in PAK and 20.1% in IAK recipients (p=0.9), predominantly due to cardiovascular disease.

Discussion: Treatment success of PAK versus IAK transplantation are comparable, for up to 7 years. A greater proportion of PAK achieved insulin independence, but also CGF.