A continuous glucose monitoring system tracks glucose levels throughout the day and night using a small sensor placed on the skin. It transmits data wirelessly to a display device or smartphone. CGMs show trends, alerts for high/low glucose, and eliminate frequent finger-stick checks. They help clinicians and patients adjust diet, activity, and medications. These systems use enzymes that react with glucose in the interstitial fluid for accurate readings. Many models integrate with apps for retrospective data review. They are invaluable for tight glucose control, especially in Type 1 diabetes. Some include predictive alarms for hypoglycemia. Sensors typically change every 7–14 days. Useful in education, monitoring therapy responses, and managing complications.