Continuous Glucose Monitoring and Flash Glucose Sensing are exciting new technologies popular with many patients and their parents who are keen to have access to such technologies. However such technologies are costly and it is important that clinicians identify patients who are most likely to benefit and ensure that families have appropriate training in order to optimise their use. The aims of this overview are firstly to review the evidence underpinning CGMS and to discuss the magnitude of potential gains in terms of improving HbA1C, reducing hypoglycaemia and reducing anxiety-in particular regarding hypoglycaemia. Secondly the relevant NICE guidance, ACDC guidelines and regulatory framework around their implementation and withdrawal if ineffective will be discussed. Finally the practical application of these technologies will be examined with particular emphasis on patient training and education packages and on the utilisation of more advanced features such as rate of change indicators in order to optimise the potential clinical benefit on glycaemic control and on hypoglycaemia within diabetes clinics.