Untreated corns can cause severe pain and infection under long-term friction, deformity of the foot, and erosion of the foot in diabetic patients. 1. Causes severe pain and infection symptoms: corns can compress the nerve endings, so untreated, there will be pain in the walking process, and even pus and red, swollen, hot and painful infection symptoms. 2. Causing foot deformity: corns are not treated in time after appearing, and there is pain when walking. In order to avoid the pain, will consider changing the walking habits, over time will lead to foot deformity. 3. Foot erosion: if corns are combined with diabetes and not treated in time, once broken, it will affect the surrounding tissues, resulting in erosion, and the situation may be serious enough to require amputation. It is recommended to go to the regular hospital in time to receive treatment at the early stage of corns, because the harm is greater in the later stage.