An apparatus comprising a user interface configured to generate an electrical signal to begin determination of an effective correction factor when prompted by a user, an input configured to receive sampled blood glucose data of a patient that is obtained during a specified time duration, including a time duration after delivery of an initial insulin correction bolus, and a controller in electrical communication with the input and the user interface. The controller includes a correction factor module configured for determining an effective correction factor according to an amount of insulin in the initial insulin correction bolus and a decrease in the blood glucose level determined using the sampled blood glucose data. Other devices and methods are disclosed.