A system comprising: a continuous glucose monitoring, CGM, system including a sensor; and a wearable device for providing information to a user regarding the user's blood glucose value, the wearable device comprising: a communication module having an I/O port for receiving data transmitted from the CGM system including the sensor, a signal from the sensor transformed into the data for transmission; and a display configured to display information based on the received signal for a set duration; wherein: the wearable device further comprises an input device for enabling the user to acknowledge that the information has been viewed; when the user acknowledges that the information has been viewed, the communication module is arranged to send an acknowledgement signal to the CGM system; and if the user does not acknowledge that he or she has received information indicating that the user's glucose is dangerously high or low, or is trending dangerously high or low, the CGM system is arranged to provide one or more alerts to the user and/or to one or more third parties. a continuous glucose monitoring, CGM, system including a sensor; and a wearable device for providing information to a user regarding the user's blood glucose value, the wearable device comprising: a communication module having an I/O port for receiving data transmitted from the CGM system including the sensor, a signal from the sensor transformed into the data for transmission; and a display configured to display information based on the received signal for a set duration; wherein: the wearable device further comprises an input device for enabling the user to acknowledge that the information has been viewed; when the user acknowledges that the information has been viewed, the communication module is arranged to send an acknowledgement signal to the CGM system; and if the user does not acknowledge that he or she has received information indicating that the user's glucose is dangerously high or low, or is trending dangerously high or low, the CGM system is arranged to provide one or more alerts to the user and/or to one or more third parties. a communication module having an I/O port for receiving data transmitted from the CGM system including the sensor, a signal from the sensor transformed into the data for transmission; and a display configured to display information based on the received signal for a set duration; wherein: the wearable device further comprises an input device for enabling the user to acknowledge that the information has been viewed; when the user acknowledges that the information has been viewed, the communication module is arranged to send an acknowledgement signal to the CGM system; and if the user does not acknowledge that he or she has received information indicating that the user's glucose is dangerously high or low, or is trending dangerously high or low, the CGM system is arranged to provide one or more alerts to the user and/or to one or more third parties. the wearable device further comprises an input device for enabling the user to acknowledge that the information has been viewed; when the user acknowledges that the information has been viewed, the communication module is arranged to send an acknowledgement signal to the CGM system; and if the user does not acknowledge that he or she has received information indicating that the user's glucose is dangerously high or low, or is trending dangerously high or low, the CGM system is arranged to provide one or more alerts to the user and/or to one or more third parties.