Application of continuous glucose monitoring (CGM) in diabetes management involves real-time CGM (rtCGM), intermittently scanned CGM (isCGM), and automated insulin delivery (AID) associated closed-loop systems. The rtCGM provides continuous real-time glucose data and alerts, helping improve blood glucose control and reduce the risk of hypoglycemia. The isCGM, which requires manual scanning of the sensor to obtain data, has a more simplified function but remains practical for those not needing intensive insulin therapy. The AID system integrates CGM, insulin pumps, and algorithms to automatically adjust insulin doses, forming a closed-loop control that significantly enhances blood glucose stability. Research shows these technologies can effectively improve HbA1c, increase Time in Range (TIR), and reduce the risk of acute complications. In summary, despite challenges such as skin reactions, drug interference, and accessibility, the combination of continuous glucose monitoring and closed-loop systems enables personalized medical choices and plays an important role in empowering patients with diabetes.