Pre-Transplant C-Peptide Level and Post-Transplant Outcomes

Pancreatic beta-cells produce insulin by cleavage of a prohormone precursor into equal parts insulin and C-peptide. When administered to patients with type 1 diabetes, C-peptide is known to have renoprotective properties, including decreasing microalbuminuria, reduced hyperfiltration injury, and regression of diabetic histologic changes on kidney biopsy. There are few data available on the relationship between pretransplant C-peptide levels and outcomes following kidney transplantation.

J. Vinson and K. Tennankore of the Nova Scotia Health Authority division of nephrology, Halifax, Nova Scotia, Canada, conducted a retrospective cohort study to identify the association of pretransplant C-peptide levels dichotomized around the median and (1) delayed graft function; (2) proteinuria; and (3) median estimated glomerular filtration rate (eGFR) at 1 year post-transplant. Results of the study were reported during a virtual session at the 2012 American Transplant Congress in a presentation titled The Association of Pre-Kidney Transplant C-Peptide Level with Post-Transplant Outcomes.

The study also examined C-peptide level as a continuous variable categorized into quartiles. The association between pre-transplant C-peptide level and eGFR at 1-year post-transplant was determined using multivariable linear regression.

Pre-transplant mean and median C-peptide levels were 3458 and 3118 pmol/L. respectively; in an initial analysis, pre-transplant C-peptide level was dichotomized at 3000 pmol/L. Among patients with low C-peptide levels, the incidence of delayed graft function was higher than in patients with C-peptide levels ≥3000 pmol/L  (8/31 [25.8%] vs 6/33 [18.2%], respectively). At 1-year, eGFR was lower in the group with C-peptide levels <3000 than in those in the ≥3000 pmol/L group (49.8 mL/min/1.73 m2 vs 60.0 mL/min/1.73 m2; P=.0877).

When C-peptide level was categorized based on quartile, there was also a steady increase in eGFR from the lowest to the highest quartile (46.5 mL/min/1.73 m2 [C-peptide level ≤1940 pmol/L] to 57.3 mL/min/1.73 m2 [C=peptide level >4616 pmol/L]).

In analyses treating C-peptide as a continuous variable, the association between pre-transplant C-peptide and eGFR at 1-year post-transplant reached statistical significance (coefficient=0.0043; 95% confidence interval 0.00038-0.0081; P=.032).

“A higher pre-transplant C-peptide level is associated with a lower risk of delayed graft function, and a higher eGFR and lower proportion with proteinuria at 1 year after kidney transplant,” the authors said.

Source: Vinson, A.J., Tennankore K. The association of pre-kidney transplant C-peptide level with post-transplant outcomes. Abstract of a presentation at the virtual 2021 American Transplant Congress (Abstract #912), June 5, 2021.