C-peptide Trajectory Following Pancreas Transplantation

Pancreas transplantation is the most reliable management of insulin-dependent diabetes mellitus, offering sustained glycemic control with a reduction in diabetes-related complications. Despite recent advancements, recipient selection criteria are not standardized. Historically, pre-transplant C-peptide level was an important indicator of post-transplant success, yet conflicting data exist regarding their correlation. This study explores post-transplant C-peptide trends in recipients with varying pre-transplant C-peptide levels, aiming to elucidate its impact on patient and graft survival.

A retrospective review of 78 pancreas transplant recipients (simultaneous pancreas and kidney, pancreas after kidney, and pancreas transplant alone) from September 2012 to August 2022 was conducted. Patients were categorized based on pre-transplant C-peptide levels (>4.0 ng/mL elevated vs. ≤4.0 ng/mL low/normal). C-peptide levels, HbA1c, and estimated glomerular filtration rate (eGFR) were monitored at specified intervals post-transplant.

The two cohorts exhibited disparate post-transplant C-peptide trends; elevated (pre-transplant: mean = 8.43 ng/mL, range = 4-28.26 ng/mL; post-transplant: mean = 3.57 ng/mL, range = 0.84-8.53 ng/mL) and low/normal (pre-transplant: mean = 1.07 ng/mL, range = 0-3.92 ng/mL; post-transplant: mean = 2.81 ng/mL, range = 0.9-6.73 ng/mL). Despite achieving normoglycemic control (HbA1c 5.26% and 5.19%, respectively), the decline in C-peptide levels in the elevated pre-transplant group contradicted the anticipated outcomes.

This study highlights the intricate dynamics of post-transplant C-peptide, revealing unexpected patterns in recipients with elevated pre-transplant C-peptide levels. The study's findings question the predictive value of pre-transplant C-peptide levels and underscore the importance of further research to unravel its metabolism post-transplant.