The FreeStyle Libre flash glucose monitor became available on prescription (subject to local health authority approval) in all four nations of the UK from November 2017, a watershed moment in the history of diabetes care. Calibration free, the FreeStyle Libre is a disc worn on the arm for 14 days which is designed largely to replace the recommended 4-10 painful finger-stick blood glucose tests required each day for the self-management of diabetes. This review discusses clinical data from randomized and observational studies, considers device accuracy metrics and deliberates its popularity and the potential challenges that this new device brings to diabetes care in the UK. In randomized trials, FreeStyle Libre use is associated with a reduction in hypoglycaemia and, in observational studies, improvements in HbA1c levels. User satisfaction is high and adverse events are low. Accuracy of the FreeStyle Libre is comparable to currently available real-time continuous glucose monitors in adults, children and during pregnancy; the cost of the FreeStyle Libre is lower. Glucose data can be visualized in multiple devices and platforms, and summarized in an ambulatory glucose profile to aid pattern recognition and insulin dose adjustment. There is a need for appropriate education, of both users and healthcare professionals, to harness the full benefits. Further randomized studies to assess the long-termimpact on HbA1c , particularly in those with high baseline HbA1c and in specific age groups, such as adolescents and young adults, are warranted. The potential impact on complications, is yet to be realized.