A device for generating alerts for Hypo and Hyperglycemia Prevention from Continuous Glucose Monitoring (CGM) determines a dynamic risk based on both information of glucose level and a trend obtainable from a CGM signals. The device includes a display whose color depends on the DR (for example, red for high DR, green for low risk). When DR exceeds a certain threshold, alerts are generated to suggest the patient to pay attention to the current glucose reading and to its trend, both of which are shown on the display in numbers and symbols (e.g. an arrow with different slope or color).