3D-printed insoles are increasingly used for the management of foot pathologies, and the recent literature reports on various experimental studies dealing with either whole foot orthoses or pads fabricated through 3D-printing processes. In the case of diabetic foot disease, the main aim is to deliver more effective solutions with respect to the consolidated processes to reduce compressive risk forces at specific plantar foot sites. Clinical studies are, however, still limited, at least in peer-review journals. Additionally, in Italy, the manufacturing process of these medical devices has not been formally integrated yet into the list of care processes approved for reimbursement by the public healthcare service. Within the Italian DIAPASON project (DIAbetic PAtients Safe ambulatiON), a feasibility pilot study has been conducted in the territory on 21 patients with diabetic foot complications to assess the pros and cons of an innovative process. The process, which relies on in-shoe pressure measurements and on a patented 3D modeling and printing procedure, includes the prescription, design, manufacturing and testing of 3D-printed personalized insoles. The process has been tested in an ambulatory setting and showed the potential to be also implemented in community settings. In this paper, we report a case study on a single volunteer, and we describe and comment on how the whole process has been proven safe and suitable for the purpose.