The limited number of self-monitoring blood glucose measurements is an obstacle for good metabolic control in patients with type 1 diabetes. However, continuous glucose measurement with real-time data and alarms is a recent technology that promises to improve the efficacy of treatment in diabetic patients. GuardianRT uses a continuous telemetry display of real-time glucose values, and automatic alerts at preset hypo- and hyperglycaemic levels. Three calibrations a day are required, and the sensor must be changed every three days. The GuardControl study showed that, within three months, real-time continuous glucose monitoring with the GuardianRT led to significantly improved HbA1c values in 162 poorly controlled patients (children and adults) with type 1 diabetes despite intensive insulin therapy. The continuous availability of glucose measurements permitted the patients to adjust their own insulin doses, food intake and physical activity and, thus, improve their glycaemic control. This report summarizes the available data on this tool and details how best to use this state-of-the-art modality in diabetic patients in clinical practice.