Introduction: Registry and single center studies indicate SPK transplantation is being increasingly offered to patients with T2D and chronic kidney disease (CKD) with results similar to T1D patients with CKD. Published studies also suggest pancreas graft survival is similar in selected patients with insulin-dependent diabetes regardless of levels of endogenous beta cell function as measured by C-peptide level. However, national policies and specific eligibility criteria at many centers may restrict allocation of SPK grafts to T2D patients who have a BMI<30kg/m2. Several concerns about offering SPK transplantation to obese T2D recipients relate to the potential for generally inferior pancreas graft outcomes in obese patients, potential for insulin resistance negatively impacting glycemic control, and potential for poorer kidney graft and patient survival compared to receiving a kidney transplant alone. Herein, we aimed to analyze SPK outcomes in obese (BMI>30) T2D patients with CKD compared to low BMI SPK recipients and kidney transplant recipients.
Methods: UNOS files were used to analyze 14154 primary, adult deceased donor kidney (DDKI, n=10064), living donor kidney (LDKI,n=4003) and SPK (n=87) transplants performed in the US in recipients with a BMI>30 between 2004-2014. Donor and recipient demographics were compared and kidney graft survival, (KGS) death censored kidney graft survival (DCKGS) and patient survival (PS) were analyzed excluding <30d technical graft failures. In addition, SPK recipients with a BMI>30 were compared to those with a BMI<30 (n= 500). Multivariate (MV) models were used to determine if donor category and recipient BMI, among other donor and recipient variables, played a role in outcomes.  
Results: By univariate analyses, KGS in T2D patients with BMI>30 was similar between SPK recipients and LDKI recipients (5 yr: 84.7% vs. 81.4%, p=0.71) and both were significantly better than for DDKI recipients (5 yr: 69.3%, p<0.0001 and p=0.01). The same pattern was observed for DCKGS (5 yr. SPK: 92.2% vs. LDKI: 91.8% vs. DDKI: 84.8%, p<0.001) and PS (5 yr. SPK:91.9% vs. LDKI: 87.1% vs. DDKI: 78.5%). Analyzing the entire T2D recipient cohort of 29588 patients using MV modeling, recipient BMI was not a significant factor for KGS (HR:0.998, CI:0.992-1.003, p=0.448) but had some impact on DCKGS (HR:1.012, CI:1.003-1.021, p=0.0058) and PS (HR:0.991, CI:0.984-0.997, p=0.0073), whereas donor type, donor and recipient age, donor and recipient ethnicity, pretxp dialysis, and HLA mismatch had a significant impact.  KDRI was also a significant factor in DDKI vs. SPK grafts affecting KGS, DCKGS and PS in both the total cohort and BMI>30 cohort in MV analysis. Comparing outcomes in T2D SPK recipients between those with a BMI>30 and <30, KGS, DCKGS, and PS were not statistically different.
Conclusions: In this retrospective analysis of UNOS data, comparable outcomes in selected T2D SPK recipients can be achieved in patients with a BMI>30 or with a BMI < 30. Moreover, that kidney and patient survival rates in obese T2D recipients are similar between SPK and LDKI, and superior to that of DDKI suggests that BMI should not be the sole or main criteria for excluding this population from receiving an SPK. Hence, employing a BMI cutoff of 30 for offering T2D/CKD patients an SPK transplant appears unjustified by the data. T2D/CKD patients without an available LDKI will experience a shorter waiting time and receive a better quality kidney with an SPK transplant than a DDKI transplant.