The Guardcontrol Trial: Study to Assess if Type 1 Diabetics Can Improve Using the Real-time Values of Guardian RT

Inclusion Criteria: * Patient has signed Informed consent form prior to Study Entry. * Patients have been diagnosed with type 1 diabetes mellitus (DM) at least 12 months prior to Study Entry. * HbA1c must be 8.1% or above at study entry day (central lab value). * Patients must perform at least two self-monitoring blood glucose finger-sticks daily. * Patients are on intensive insulin therapy; for multiple daily injections (MDI) patients specifically, be on a schedule of a minimum of 3 injections daily. * Patients on intensive insulin therapy must be on continuous subcutaneous insulin infusion (CSII) or MDI at least 3 months prior to inclusion and should have been receiving diabetes care from the investigator of each centre for the 6 months prior to inclusion. * Patients must be using only insulin analogues or rapid-acting human insulin for their meal boluses. * Patients are willing to undergo all study procedures. * Patients are trained on how to adapt their insulin dose to their meals and are knowledgeable concerning how to calculate and apply corrective insulin boluses post-prandially, as well as on the influence of physical activity and other life style factors on their glycemia. * Patients are willing to participate in a Guardian® RT product training course * Patients understand how to adjust and administer corrective treatment. Exclusion Criteria: * Patient has hearing problems/is deaf. * Patient has impaired vision/blindness so screen alarms cannot be recognized. * Alcohol or drug abuse other than nicotine. * Allergy to sensor or components of the sensor. * Manifest psychiatric disturbances. * Patients suffering from cancer, heart failure, kidney disease and other chronic debilitating conditions. * Patient does not have a reliable support person. * Patient is unwilling or unable to comply with the provisions of the protocol. * Patient has scheduled travel on a plane in the next 3 months. * Patient has scheduled a vacation which will occur between Visit 1 and Visit 2. * Patient is participating in another device or drug study. Subject must have completed the follow-up phase of any previous study at least 30 days prior to enrollment in this trial. The subject may only be enrolled in this study once. Patient has already participated in the Centre Qualification Phase.