Transplantation for Type I Diabetes: Comparison of Vascularized Whole-Organ Pancreas With Isolated Pancreatic Islets

Type I diabetes mellitus afflicts nearly 2 million Americans and is responsible for untold morbidity. Despite significant improvements in monitoring and administration, insulin therapy cannot fully normalize glucose homeostasis at the present time. Therefore, curative therapies for the disease have relied on replacement of the β-cell mass by transplantation. During the last 35 years, whole organ pancreas transplantation (WOP) has evolved gradually into a highly effective therapy for type I diabetic patients who are undergoing simultaneous renal transplantation.1–5 Because the risks of severe complications of this procedure are relatively small in these patients who are already obligated to lifelong immunosuppression, the benefits of the procedure are generally accepted as outweighing the risks.6 In recent years, WOP has also been advocated for type 1 patients with diabetes who have either adequate function of their own kidneys or an established renal transplant. In these cases of pancreas transplant alone or pancreas after kidney transplantation (PAK), very poor glucose control and dangerous episodes of hypoglycemic unawareness are the usual and most persuasive indications for transplantation. These pancreas without kidney transplants remain controversial despite the success of the simultaneous pancreas and kidney transplant procedure (SPK), with at least one recent analysis suggesting that the risks of these procedures may outweigh their benefits.7 IIT offers a less invasive and thus presumably less morbid alternative to WOP for β-cell replacement, although the success of this procedure was considered exceedingly rare until relatively recently.8 By the 1990s, a number of centers using improved methods of islet isolation demonstrated that IIT quite often resulted in sustained insulin secretion. Nevertheless, insulin independence at 1 year post-transplantation remained unusual ( 90% of patients.14 However, in the other 6 centers, success was sporadic (0–50%), probably due to the complexity of the isolation technique and the need for additional experience.15 The success and relative safety of the Edmonton trial has led some to suggest that IIT is ready to supersede WOP as the procedure of choice for replacement of β-cells in type I diabetic patients. Such a contention has important implications in schemas for cadaveric pancreas organ use, because candidates for WOP are currently given priority over potential IIT recipients. Thus, it is important to compare the 2 transplant methods. We have examined a contemporary series of WOP and IIT at our institution to compare relative efficacy, safety, and cost.