Embodiments include methods and systems for maintaining glucose homeostasis. Systems can include a pump, a first reservoir including a homeostasis agent, an umbilical catheter capable of being advanced in the umbilical vein or in the falciform ligament, and a sensor. Systems can also include a biocompatible coating, a microprocessor in communication with the pump and the sensor, and a power supply. Methods can include implanting a pump and reservoir subcutaneously in a patient, advancing a catheter in the umbilical vein or in the falciform ligament, measuring a blood glucose level, pumping a homeostasis agent, and administering the homeostasis agent to the portal venous system.