Simultaneous Pancreas-Kidney Transplantation Versus Kidney Transplantation Alone in Type 1 Diabetes: Does Pancreas Transplantation Improve Clinical Outcomes? A Systematic Review and Exploratory Meta-Analysis

Background: Simultaneous pancreas–kidney transplantation (SPKT) restores both renal function and endogenous insulin secretion in selected patients with type 1 diabetes mellitus (T1DM) and end-stage renal disease (ESRD). Whether SPKT provides superior patient survival, kidney graft outcomes and cardiovascular benefit compared with kidney transplantation alone (KTA) remains debated, particularly when KTA is performed from a living donor. Methods: A systematic review was conducted according to PRISMA 2020 guidelines. PubMed/MEDLINE was searched using a predefined strategy including terms related to pancreas transplantation, kidney transplantation alone, T1DM, and ESRD/chronic kidney disease. Eligible studies included adult T1DM/ESRD populations comparing SPKT with KTA, including living-donor kidney transplantation (LDKT) and deceased-donor kidney transplantation (DDKT) and reporting clinically relevant outcomes. Full texts were reviewed and categorized as core comparative evidence, secondary/supportive evidence or excluded records. A quantitative synthesis was additionally performed for studies reporting directly comparable adjusted hazard ratios for patient mortality and kidney graft failure in the SPKT versus LDKT comparison. Results: Nineteen observational studies met the inclusion criteria and were included in the qualitative synthesis. SPKT consistently provided superior metabolic control and insulin independence when pancreas graft function was maintained. Compared with deceased-donor or mixed KTA cohorts, SPKT was frequently associated with more favorable long-term patient survival and cardiovascular outcomes in selected recipients. However, comparisons with LDKT yielded less consistent results, with several registry-based analyses reporting equivalent or superior kidney graft and survival outcomes after living-donor transplantation. Quantitative synthesis of the two studies providing directly comparable adjusted hazard ratios demonstrated a higher risk of patient mortality (HR 1.30, 95% CI 1.10–1.54) and kidney graft failure (HR 1.43, 95% CI 1.24–1.66) following SPKT compared with LDKT. Formal meta-analysis of SPKT versus DDKT was not feasible because of substantial heterogeneity in outcome definitions, statistical reporting methods and follow-up duration across studies. Conclusions: In adults with T1DM and ESRD, successful SPKT provides a durable metabolic advantage and may improve long-term outcomes compared with deceased-donor KTA in selected patients. Across analyses that included all transplanted recipients from the time of surgery (intent-to-treat), early perioperative risk is higher after SPKT but may be offset over time when pancreas graft function is maintained. Evidence does not support a universal survival superiority of SPKT over living-donor kidney transplantation. Our quantitative synthesis of intent-to-treat, transplant-date analyses indicates that LDKT is associated with lower risks of patient mortality and kidney graft failure compared with SPKT when a suitable living donor is available. Treatment decisions should be individualized, considering living-donor availability, anticipated waiting time and dialysis exposure, cardiovascular and surgical risk, and the likelihood of durable pancreas graft function, with greater weight given to contemporary cohorts.