Alarms in continuous glucose monitoring systems (CGM) represent a very important feature enabling to patients with diabetes who use these systems to keep their blood glucose level in the target range and to avoid excursion to hypoglycemia or hyperglycemia. The possibility to warn the patient that the target range has been crossed means one of the main advantages of CGM over the selfmonitoring of blood glucose with personal glucometers, but also (so far) flash glucose monitoring systems. However, there is surprisingly few studies concerning specifically the relationship between the alarms settings and glucose control. Therefore, there are currently no recommendations nor guidelines for optimal settings of alarms in CGM. Limited number of studies suggest that the setting of the hypoglycemia alarm to a level higher than 4 mmol/L is associated with lower frequency and shorter duration of hypoglycemia, and may be temporarily increased to 6 mmol/L in patients with impaired hypoglycemia awareness.