Diabetes mellitus significantly increases the risk of severe secondary complications such as lower extremity amputations. Custom insoles are routinely prescribed to mitigate plantar pressure and prevent ulcerations, but traditional fabrication techniques have been largely inefficient. Recent advances in 3D printing technology have revolutionized the production of custom insoles. We have utilized personalized metamaterials, designed through topology optimization (TO), which allows precise adjustments in stiffness to improve comfort and effectiveness. These metamaterials allow for precise adjustments in stiffness and can be tailored through geometrical variations using the same base material, enhancing comfort and effectiveness. Additionally, the smart custom insole, equipped with strategically placed pressure sensors, provides real-time data on plantar pressure, accommodating joint movements and deformities. This data forms the basis of the insole design, ensuring each insole is perfectly adapted to the user’s specific needs. This innovative approach results in personalized insoles with customized TO metamaterial lattices, demonstrating reduced plantar pressure and enhanced prevention of diabetic foot ulcers.