In this paper, we introduce MedGuard, a novel compiler polymorphism technique designed to enhance the security of medical IoT devices. Medical IoT devices, including wearable medical devices (WMDs), are increasingly becoming targets for sophisticated cyber-attacks due to their critical role in healthcare settings. MedGuard aims to prevent the scalability of such attacks across similar devices by generating unique executable binaries from a combination of source code and random seeds. This technique not only strengthens individual device security but also incorporates future-ready mechanisms like detection traps. Our approach significantly raises the security posture of medical IoT ecosystems, safeguarding both hospital networks and patient home environments. This paper details the implementation, effectiveness, and potential future enhancements of MedGuard, demonstrating its crucial role in advancing medical IoT security.