In one implementation, an insulin delivery system using an on-body network includes an insulin delivery device that is adapted to administer dosages of insulin to a patient; a controller that is adapted to control operation of the insulin delivery device, to establish a first network connection in which the controller acts in a central role, and to establish a second network connection in which the controller acts in a peripheral role; one or more peripheral devices that are adapted to generate patient data related to blood glucose levels and to transmit the patient data wirelessly over the first network connection, the peripheral devices acting in a peripheral role over the first network connection; and a mobile application installed on a mobile computing device that is programmed to communicate with the controller over the second network connection, the mobile application communicating in a central role over the second network connection.