Aim of Study: Pancreas transplantation has historically been reserved for patients with progressive secondary complications of Type 1 Diabetes Mellitus (DM1). However, case reports from several large-volume pancreas transplant programs have suggested that select patients with Type 2 Diabetes Mellitus (DM2) also benefit from pancreas transplantation with similar patient and allograft survival rates. However, it remains to be clarified whether DM2 recipients achieve comparable glycemic control to DM1 patients on account of their varying degrees of insulin resistance. This study aims to compare and contrast glycemic control in consecutive pancreas transplants performed at a high volume pancreas transplant center in both DM1 and DM2 patients.
Methods: A retrospective review was performed of 50 consecutive patients receiving a simultaneous pancreas-kidney transplant (SPK) or pancreas after kidney transplant (PAK) between 2013 and 2016. Patients were divided into DM1 and DM2 cohorts based on c-peptide detection and clinical history. DM2 selection criteria included age <55yr, BMI <30kg/m2, insulin dependence with requirements not exceeding 1U/kg of IBW/day, and fasting c-peptide <10ng/mL. Fasting blood glucose levels (FG) at multiple time points after transplantation were collected. Multiple 2-tailed t-tests were then performed to compare cohorts.
Results: 50 consecutive pancreas transplant recipients were evaluated. 29 patients were DM1 (58%) and 21 were DM2 (42%). There was no statistical difference in terms of gender, mean age, or other demographic data between groups. Depleting induction therapy was used in all patients along with maintenance immunosuppression consisting of tacrolimus and mycophenoate mofetil. Tacrolimus blood levels were similar between cohorts. Acute rejection rates were 6.8% and 4.7% (p=NS) in DM1 and DM2 recipients, respectively. At 6 weeks post-transplant, the mean FG was 110mg/dL in DM1 cohort vs 105mg/dL (p=NS) in the DM2 cohort. At 6 months post-transplant, mean FG was identical (105mg/dL) in the DM1 and DM2 cohorts, respectively. At 12 months post-transplant, mean FG was 98mg/dL and 108mg/dL (p=NS) in the DM1 and DM2 cohorts, respectively.
Conclusions: DM2 patients achieved similar glycemic control as measured by FG compared to the DM1 group. In carefully selected non-obese DM2 patients, we postulate that the density of islet cells in a solid organ pancreas provides a sufficient amount of insulin to overcome mild to even moderate amounts of insulin resistance and achieve comparable transplant outcomes. Nonetheless, it remains to be determined to what extent insulin resistance in DM2 pancreas recipients may still influence transplant outcomes. Future studies with longer follow-up are needed to clarify the durability of excellent glycemic control in this complex DM2 patient population.