Systems and methods for medicine delivery

A device for measuring delivered dose information comprising:

• an insulin delivery device having a proximal end and a distal end, a plunger and an insulin vial comprising insulin distal of said plunger;
• a two-part pen cap, comprising:
• a sleeve enclosing the insulin delivery device, lockable onto the insulin delivery device and comprising at least one light emitter and a plurality of light sensors, wherein the at least one light emitter is oriented to project light through insulin in the insulin vial to the light sensors;
• a second portion attaching to the sleeve and enclosing the distal end of the insulin delivery device;
• and
• a locking hub for locking the sleeve to the insulin delivery device;
• wherein the second portion is adapted to reveal the distal end of the insulin delivery device while the first sleeve remains on the insulin delivery device during an injection;
• wherein the at least one light emitter is positioned on the sleeve to project light through insulin in the insulin vial during the injection and the plurality of light sensors are positioned to receive light projected through insulin in the insulin vial to measure a dose delivered during the injection;
• and
• wherein the sleeve is programmed to detect when the plunger stops and to provide a signal indicating a successful dose after a predetermined period elapses after the plunger stops during which a skin detector detects contact of the insulin delivery device with skin.