A system comprising: an insulin delivery device configured to deliver insulin to a user of the system; a glucose monitor; and a computer-based control unit having a user interface and a computer-based processor, wherein the user interface enables a caregiver to specify parameters associated with a discretionary delivery of insulin that may be delivered to the user, wherein the glucose monitor subsequently monitors a glucose level of the user during a period of time associated with the discretionary delivery and sends data representing the monitored glucose level to the computer-based processor, wherein the computer-based processor automatically determines, based on the data received from the glucose monitor, if, when and how much discretionary insulin should be delivered to the user during the period of time associated with the discretionary delivery, wherein the computer-based processor is further configured to constrain delivery of the discretionary insulin delivery based on each of the following constraints, alone or in combination: that a maximum rate of insulin delivery not be exceeded; that no more than a maximum amount of insulin be delivered during a specific window of time; that at least a minimum rate of insulin delivery be maintained; and that at least a minimum amount of insulin be delivered to the user during a specified period of time; wherein the insulin delivery device delivers insulin to the user during the period of time associated with the discretionary delivery according to the automatic determination; and wherein the system is configured to deliver insulin to the user according to a non-discretionary insulin delivery schedule unless a discretionary insulin delivery mode has been triggered. an insulin delivery device configured to deliver insulin to a user of the system; a glucose monitor; and a computer-based control unit having a user interface and a computer-based processor, wherein the user interface enables a caregiver to specify parameters associated with a discretionary delivery of insulin that may be delivered to the user, wherein the glucose monitor subsequently monitors a glucose level of the user during a period of time associated with the discretionary delivery and sends data representing the monitored glucose level to the computer-based processor, wherein the computer-based processor automatically determines, based on the data received from the glucose monitor, if, when and how much discretionary insulin should be delivered to the user during the period of time associated with the discretionary delivery, wherein the computer-based processor is further configured to constrain delivery of the discretionary insulin delivery based on each of the following constraints, alone or in combination: that a maximum rate of insulin delivery not be exceeded; that no more than a maximum amount of insulin be delivered during a specific window of time; that at least a minimum rate of insulin delivery be maintained; and that at least a minimum amount of insulin be delivered to the user during a specified period of time; wherein the insulin delivery device delivers insulin to the user during the period of time associated with the discretionary delivery according to the automatic determination; and wherein the system is configured to deliver insulin to the user according to a non-discretionary insulin delivery schedule unless a discretionary insulin delivery mode has been triggered. that a maximum rate of insulin delivery not be exceeded; that no more than a maximum amount of insulin be delivered during a specific window of time; that at least a minimum rate of insulin delivery be maintained; and that at least a minimum amount of insulin be delivered to the user during a specified period of time; wherein the insulin delivery device delivers insulin to the user during the period of time associated with the discretionary delivery according to the automatic determination; and wherein the system is configured to deliver insulin to the user according to a non-discretionary insulin delivery schedule unless a discretionary insulin delivery mode has been triggered.