Flexible polymeric materials and wearable biosensors for smart diabetes mellitus diagnostics and monitoring.

Diabetes mellitus remains a major global health challenge that requires frequent and accurate glucose monitoring. Conventional finger-prick methods are invasive and often lead to poor patient compliance. In response, flexible and wearable biosensors have emerged as promising platforms for continuous and non-invasive glucose monitoring. This review provides a critical and framework-driven analysis of polymer-based material systems underpinning wearable glucose biosensors, including conductive polymers, biocompatible/biodegradable polymers, elastomers, hydrogels, and polymer-nanomaterial hybrids. We discuss how polymer properties govern electron transfer, mechanical compliance, biocompatibility, and long-term stability, highlighting trade-offs and limitations of each material class. Recent advances in hybrid and smart biosensing systems integrating microfluidics, self-powered operation, Internet of Things, and artificial intelligence-assisted analytics are systematically examined. Finally, we identify key challenges, such as material degradation, biofluid variability, and integration complexity, and propose targeted future directions for material design, device development, and clinical translation.