Glucose biosensors have become essential tools in diabetes management, offering accurate and reliable blood glucose monitoring. This review discusses the history, principles, performance, and current status of glucose biosensors in clinical practice. Blood glucose monitoring is crucial for managing diabetes, and glucose biosensors have evolved significantly over the past 50 years, with improvements in point-of-care devices, continuous glucose monitoring systems, and non-invasive glucose monitoring systems. Despite these advancements, challenges remain in achieving accurate and reliable glucose monitoring. Glucose biosensors operate based on the interaction of glucose with enzymes such as glucose oxidase (GOx) or glucose-1-dehydrogenase (GDH). The most common type is the electrochemical biosensor, which measures the current generated by electron transfer. GOx is widely used due to its high selectivity and stability. GDH-based biosensors, particularly those using PQQ or NAD as cofactors, offer alternative methods with different performance characteristics. The development of glucose biosensors has progressed through several generations. First-generation sensors relied on detecting hydrogen peroxide, while second-generation sensors used redox mediators to improve performance. Third-generation sensors eliminate the need for mediators, enabling direct electron transfer between the enzyme and electrode, leading to more compact and implantable devices. Continuous glucose monitoring systems (CGMS) provide real-time data for diabetes management but face challenges such as biocompatibility and accuracy. Non-invasive glucose monitoring systems, including optical and transdermal methods, are still under development. Point-of-care testing (POCT) devices are widely used for rapid glucose measurement, with disposable test strips being the most common format. Analytical performance validation is critical for ensuring the accuracy and reliability of glucose biosensors. Standards such as those set by the ADA and FDA define acceptable error margins and performance criteria. Factors affecting performance include precision, accuracy, linearity, and resistance to interferences such as ascorbic acid and certain drugs. Despite advancements, challenges remain in achieving consistent and accurate glucose monitoring. Ongoing research focuses on improving biosensor technology, including electrode design, membrane materials, and nanomaterials. Standardization of performance criteria and continuous training for users are essential for effective diabetes management. Overall, glucose biosensors play a vital role in diabetes care, offering a balance between accuracy, ease of use, and cost-effectiveness.Glucose biosensors have become essential tools in diabetes management, offering accurate and reliable blood glucose monitoring. This review discusses the history, principles, performance, and current status of glucose biosensors in clinical practice. Blood glucose monitoring is crucial for managing diabetes, and glucose biosensors have evolved significantly over the past 50 years, with improvements in point-of-care devices, continuous glucose monitoring systems, and non-invasive glucose monitoring systems. Despite these advancements, challenges remain in achieving accurate and reliable glucose monitoring. Glucose biosensors operate based on the interaction of glucose with enzymes such as glucose oxidase (GOx) or glucose-1-dehydrogenase (GDH). The most common type is the electrochemical biosensor, which measures the current generated by electron transfer. GOx is widely used due to its high selectivity and stability. GDH-based biosensors, particularly those using PQQ or NAD as cofactors, offer alternative methods with different performance characteristics. The development of glucose biosensors has progressed through several generations. First-generation sensors relied on detecting hydrogen peroxide, while second-generation sensors used redox mediators to improve performance. Third-generation sensors eliminate the need for mediators, enabling direct electron transfer between the enzyme and electrode, leading to more compact and implantable devices. Continuous glucose monitoring systems (CGMS) provide real-time data for diabetes management but face challenges such as biocompatibility and accuracy. Non-invasive glucose monitoring systems, including optical and transdermal methods, are still under development. Point-of-care testing (POCT) devices are widely used for rapid glucose measurement, with disposable test strips being the most common format. Analytical performance validation is critical for ensuring the accuracy and reliability of glucose biosensors. Standards such as those set by the ADA and FDA define acceptable error margins and performance criteria. Factors affecting performance include precision, accuracy, linearity, and resistance to interferences such as ascorbic acid and certain drugs. Despite advancements, challenges remain in achieving consistent and accurate glucose monitoring. Ongoing research focuses on improving biosensor technology, including electrode design, membrane materials, and nanomaterials. Standardization of performance criteria and continuous training for users are essential for effective diabetes management. Overall, glucose biosensors play a vital role in diabetes care, offering a balance between accuracy, ease of use, and cost-effectiveness.