The introduction of a new technology for the management of diabetes raises questions about their actual use. This is the case with the Freestyle Libre sensor, a tool that measures the interstitial glucose levels. Some studies have provided recommendations about its use, but little is known about how users learn to use it in the daily management of the disease. This ethnographic research explores this issue in the context of a summer camp for young people living with diabetes. The results describe three different levels (material, epistemic and moral) at which learning occurs. They show that its use requires an active appropriation process, the importance of a setting that promotes interactions between the participants and that the features of the tend to reconfigure the expert-lay person relationship.