Disclosed are systems, devices, and methods, including a system that includes a processor-based device implementing at least a residual insulin (RI) determination unit configured to determine a residual insulin in the patient's body at a particular time instance based on bolus doses previously delivered to the body of the patient, each bolus dose being associated with at least one dose value and a time representative of the time that dose value was delivered to the patient's body, and based on dose dependent RI time records that each includes at least a dose value and an associated duration value representative of dose-dependent duration of therapeutic effectiveness of the associated at least the dose value. The system also includes a pump to controllably dispense the insulin from a reservoir to the body of the patient based on the residual insulin determined by the RI determination unit.