We developed a diabetes management system with a Web interface that allowed patients to transmit their physiological data using either a PC Web browser or a mobile phone capable of working with the WAP protocol. The system could generate automatic responses to input values in accordance with a set of ranges previously defined for each user. User analysis was carried out with personal and online questionnaires. During a nine-month study period on the island of Tenerife, 12 patients were recruited. On average, they used the system every 2.0 days (SD 2.1) and the doctors reviewed their patient data every 4.0 days (SD 3.9). The average number of visits to the Website was 477 per month. Users were satisfied with the continuity and self-efficacy of care, but lack of time was a drawback for 38% of them and 75% expressed a preference for sending their data via the mobile phone short message service (SMS).