Insulin pens (“injection devices”) usually require an air shot or priming the pen before injection in order to test and ensure proper pen function and check insulin flow. In principle, air shots to test and ensure proper pen function are required for all injection devices before use. Air shots to check insulin flow are necessary for some types of medicine which require dose adjustment, but not always necessary for GLP-1 receptor agonists. There should be a sufficient amount of medicine to enable users to confirm visually a stream of insulin coming from the needle tip using a trial shot. Shooting a certain amount of medicine into the air should be repeated until medicine appears from the needle tip. If medicine does not appear after several attempts, there is a possibility that the needle or injection device is defective. Users are instructed to do a 2-unit air shot because the dose accuracy applicable for a minimum unit dose of insulin is 1 unit±100% (0–2 units) in accordance with the international standards of insulin pen (ISO 11608-1) and the domestic standards in Japan (JIS T 3226-1). The 2-unit air shot has advantages including visibility of the medicine coming from the needle tip, easy initial setting, and convenience in learning/instructing how to use injection techniques. Users of injection devices should understand the purpose and importance in performing air shots. The Japan Association for Diabetes Education and Care and related companies are positively taking action to raise public awareness of the purpose and necessity of air shots.