This book provides comprehensive description and current understanding of continuous glucose monitoring (CGM). The first section focuses on the basic knowledge of CGM technology, including the principles of CGM, accuracy assessment, operation procedure, management processes, the picture-interpretation methodology of CGM, the clinical value of CGM parameters, reference values, clinical applications of CGM report and management system and clinical indications. In the second section, it describes the clinical application of CGM, including assessing blood glucose fluctuation and hypoglycemic effect, finding hypoglycemia and identifying fasting hyperglycemia. It also introduces the role of CGM in specific diseases, such as fulminant type 1 diabetes, gestational diabetes mellitus, steroid diabetes, and insulinoma. The future of CGM is discussed in the last chapter. In addition, the main feature of this book is the typical cases and hundreds of typical monitoring map analysis to introduce the complete knowledge system of CGM. It is a reference book for diabetic health care doctors to carry out clinical application and scientific research of CGM.