*Purpose: Experience with simultaneous pancreas-kidney transplant (SPKT) in uremic patients (pts) with detectable pretransplant C-peptide (Cp) levels and a “type 2” diabetes mellitus (DM) phenotype have demonstrated survival outcomes equivalent to those with type 1 (Cp negative) DM. The study purpose was to evaluate outcomes in SPKT recipients according to presence or absence of pretransplant Cp in a case-control fashion.

*Methods: Selection criteria for Cp positive (Cp+, ≥2.0 ng/ml) were similar to Cp negative (Cp-) pts. We retrospectively analyzed 215 SPKTs performed at our center between 8/02 – 5/19 and identified 41 pts who were Cp+ pretransplant (mean level 5.4 ng/ml) and compared to 41 Cp- (level undetectable) case controls matched for recipient age, gender, race, and date of SPKT. All SPKTs were performed as intent to treat with portal-enteric drainage; all pts received depleting antibody induction with FK/MMF ± steroids. Pancreas graft failure (GF) was defined as return to daily insulin therapy and kidney GF as need for dialysis.

*Results: Mean follow-up was 7.8 years. The 2 groups were well-matched for numerous donor, preservation, recipient, and immunological characteristics. Mean donor (26 Cp+ vs 23 years Cp-) and recipient (both 44 years) ages were similar. Both groups had 21 males/20 females and 19 Caucasian/20 African American/2 Hispanic pts. There was one early death secondary to infection in each group. There were no other early (<6 month) kidney GFs but there were 5 other early pancreas GFs, 3 in Cp+ and 2 in Cp- pts. 5-year pt survival (PS, 93% vs 95%), kidney graft survival (GS, 73% vs 85%), and pancreas GS (68% vs 85%, p=0.11) rates were slightly lower in Cp+ vs Cp- pts, respectively. Death-censored kidney (69% vs 73%) and pancreas GS (59% vs 81%, p=0.07) rates were also slightly lower in Cp+ vs Cp- pts, respectively. The Cp+ group had fewer deaths with functioning grafts (9.8% Cp+ vs 19.5% Cp-, p=NS) but more pancreas GFs due to either insulin resistance (9.8% Cp+ vs 0 Cp-, p=0.12) or rejection (19.5% Cp+ vs 12% Cp-, p=NS). There were no differences in outcomes according to gender or race. Post-SPKT weight gain >5 kg occurred in 76% of Cp+ vs 32% of Cp- pts (p=.0001). Mean post-SPKT weight gain was 15 kg in Cp+ vs 6.5 kg in Cp- pts (p<.001). In pts with functioning grafts, mean post-SPKT Cp (4.9 vs 2.6 ng/ml), HbA1c (5.5 vs 5.2%) and serum creatinine (1.4 vs 1.2 mg/dl) levels were slightly higher in Cp+ pts whereas mean eGFR levels (61 vs 66 ml/min/1.73 m²) were slightly lower compared to Cp- pts.

*Conclusions: In this matched case-control study, medium-term survival and functional outcomes in pretransplant Cp+ pts are slightly inferior following SPKT, with more post-SPKT weight gain and pancreas GF due to either insulin resistance or rejection in Cp+ pts accounting for differences in outcomes.

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