The Dexcom continuous glucose monitor (CGM), a small, wearable device that tracks Scharff's glucose throughout the day and night, notifies Scharff, her husband, and her sister of highs and lows. A small filament placed just below her skin has an enzyme that reacts to glucose, generating a tiny electric current that is converted into blood glucose values. She must still use finger sticks - pricking her finger to get a drop of blood for testing - three times a day to calibrate the CGM.