The study is designed to evaluate the impact of telemonitoring on the management of Diabetes Mellitus compared with outpatient usual care. From a clinical point of view, the measurements of HbA1c will be taken to assess glycaemic control and the trial will allow to investigate how telemonitoring contributes to improve Diabetes mellitus patients health-related quality of life and reduct the access to hospital facilities (re-hospitalizations, bed-days, specialistic and ER visits) and the anxiety about health conditions. A cost-effectiveness and cost-utility analysis will be carried out in order to determine if and how telemonitoring helps to limit the healthcare expenditure. The evaluation will deal also with organizational changes and task shift due to telemonitoring introduction and patients and professionals perception towards the service.