An apparatus comprising a user interface configured to generate an electrical signal to start a basal insulin rate test 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 during delivery of insulin according to a specified basal insulin rate pattern, and a controller communicatively coupled to the input and the user interface. The controller includes an insulin calculation module configured for determining at least one of an amount of basal insulin over-delivered and an amount of basal insulin under-delivered during the basal insulin rate test in trying to meet a target blood glucose baseline. Other devices and methods are disclosed.