People with diabetes are at high-risk of Ulceration and amputation. Even pressure re-distribution over the sole of their feet is, therefore, necessary to avoid further complications. Any sign of corns or callous is an indication of high pressure and the need 3D custom diabetics Orthotics.
A lot of diabetic orthotics are made from soft conforming materials such as EVA. They are then covered in moron, plasterzote or neoprene for a durable soft finish.
That said some diabetics need more offloading of pressure areas. In this case a firmer more durable material may be used such and nylon or poly.