A medication injection supervisor device, in one example embodiment, comprises a particular sleeve, the particular sleeve being designed to lock onto to a prefabricated injection pen of a particular design, a universal header designed slide onto the particular sleeve irrespective of the particular model of the prefabricated injection pen, an electronics assembly housed by the universal header, a sensor to detect an injection automatically, the sensor being communicatively coupled to the electronics assembly, a display to display injection data, and a button to allow manipulation and display of the injection data, including resetting of the time. The medication injection supervisor device can infer the completion of the injection from a plunger of the injection pen being depressed. The medication injection supervisor device can further include a dosage reading system to read a dosage of medication delivered by the prefabrication injection pen, the dosage reading system including a clip specific to the prefabricated injection pen coupled to a plunger of the prefabricated injection pen, the dosage being determined by a position of the clip. The medication injection supervisor device can further include a micro optics subsystem communicatively coupled to the electronics assembly and having a dial reader to take one or more images of a dosage dial of the prefabricated injection pen, and an imaging subsystem communicatively coupled to the electronics assembly to recognize characters in the images taken by the dial reader.L'invention porte, selon un mode de réalisation donné à titre d'exemple, sur un dispositif de supervision d'injection de médicament qui comprend un manchon particulier, le manchon particulier étant agencé pour se verrouiller sur un stylo injecteur préfabriqué et d'un agencement particulier, une tête universelle agencée coulissante sur le manchon particulier indépendamment du modèle particulier du stylo injecteur préfabriqué, un ensemble électronique logé
