Novel Methods of Insulin Replacement: The Artificial Pancreas and Encapsulated Islets

Type 1 diabetes represents 5-10% of patients with diabetes worldwide. The importance of tight glycemic control has been demonstrated definitively in the Diabetes Control and Complications Trial but is often elusive for patients because of the associated risk of hypoglycemia. Care for these patients requires coordination amongst a variety of health professionals including primary care providers, endocrinologists, nephrologists, ophthalmologists, pharmacists, podiatrists and others. The 21(st) century is witnessing emerging and exciting treatment options for this disease. Previous attempts at curative therapy have included pancreas or islet transplantation, but limitations of organ availability and the risk associated with immunosuppression have resulted in renewed efforts for novel methods of insulin replacement. Advancement in technology has resulted in several versions of an artificial pancreas-technology that uses a continuous glucose monitor to sense the blood sugar, transmit those numbers to a control algorithm that then doses insulin ± glucagon in response to changes in blood sugar. Free living experiments with two versions of the artificial pancreas have recently been published. A quest for a bioartificial pancreas has been ongoing as well. In this system, islets (porcine, human, or embryonic stem cell derived) are encapsulated in a biocompatible device that is either a macrocapsule or a microcapsule. The benefits of this system allows for replacement therapy without immunosuppression. Human trials with encapsulation are currently ongoing. This review will provide a detailed review of artificial and bioartificial pancreas systems with a focus on human trials.