Continuous, automated and non-invasive blood glucose monitoring systems have long been a goal to assist management of diabetes mellitus. The first continuous, albeit invasive, device available in Australia is the Medtronic MiniMed Continuous Glucose Monitoring System (CGMS), which is available for physician-supervised use to give a continuous blood glucose profile (5-minutely readings, viewable only after download by the physician) for periods of 72 h. With the availability of this technology, there is a need to assess the accuracy, reproducibility and ability to detect significant clinical events (particularly hypoglycaemia) and blood glucose patterns. The question of whether this technique allows long-term improvement of metabolic control also arises. We present four case studies to illustrate the use of CGMS in clinical practice and have reviewed the rapidly emerging literature. We conclude that CGMS is a useful clinical tool in the management of diabetes mellitus, provided that it is appropriately applied and the limitations are understood.