Continuous glucose monitors: the long-awaited watch dogs? 
To date, several continuous glucose sensors have been developed and launched in the U.S. and European markets, though large-scale application in standard diabetes care still awaits its breakthrough.  This report offers an overview of the current applications and clinically relevant aspects of continuous glucose monitors (CGMs), e.g., the calibration procedure, interpretation of continuous glucose data, and some important limitations.  It is still difficult to state with certainty that CGMs allow effective improvement in glycemic control for the majority of patients with type 1 diabetes, in view of the paucity of controlled studies showing an impact on hemoglobin A1c or frequency of hypoglycemia, even if such a tendency seems to emerge from most non-controlled intervention trials.  Future controlled trials should also take into account patient-related outcomes, to evaluate the effect of CGMs on health status, treatment satisfaction, and fear of hypoglycemia.  Increased accuracy and reimbursement are key to further implementation of CGMs.