Patients with Type 1 Diabetes mellitus using FreeStyle LibreTM System (FL), a isCGM device, that attended the “Insulin Infusion Pump clinic” at Centro Hospitalar de São João were enrolled and evaluated for sociodemographic and clinical characterization, beliefs and concerns about Diabetes Mellitus, as well as isCGM’s perceptions. The gene discussed is INS; the disease is type 1 diabetes mellitus.