A system for performing diabetes self-care using at least two devices in communication with one another, comprising (a) a blood glucose monitoring device, including (i) a receptacle for receiving an amount of blood sufficient for the monitoring device to run a blood glucose test sequence, (ii) processing circuitry for controlling a blood glucose test sequence and computing a blood glucose level, (iii) a power source for powering the blood glucose monitoring device, and (b) a portable microprocessor-based device directly coupled with the blood glucose monitoring device for receiving blood glucose test results directly from the blood glucose monitoring device, including (i) a microprocessor that runs according to program instructions stored in a memory for performing analysis of the blood glucose test results, and detecting a need for a change in insulin dosage, (ii) a memory for (A) recording the recorded blood glucose test results, (B) containing programming for establishing a data protocol that allows digital data signal processing, (C) performing analysis of blood glucose, and (D) storing time and date tagged glucose test results and calibration information.