Self-management of type 1 diabetes (T1D) is a difficult task that involves different actions and decisions and requires various types of knowledge. Nowadays, it can be done partly autonomously, using a mobile digital device that measures the level of blood glucose. The FreeStyle Libre, launched on the Swiss market in 2016, is one such device. Drawing on Science and Technology Studies and adopting a sociocultural approach to learning, the present study investigated how healthcare professionals and young people living with T1D learned to use this new device during a summer camp. Based on field observations and interviews, results showed that through the mediation of others, an appropriation space was created. Through distributed expertise involving different actors, practices and types of knowledge, the users learned technical and procedural knowledge, and much more besides. In particular, they learned to cope with uncertainty, sidestep obstacles, and trust the device, gaining knowledge about diabetes itself in the process and grasping the potential contribution of the new data provided by this device to therapeutic decisions. By drawing on an explicit theory of learning that considers learning to be a context-bound activity, the present study will inspire the development of new practices in health education.