Common causes of numbness in the big toe include diabetic peripheral neuropathy, lumbar spine disease, peripheral vascular disease, rheumatoid arthritis and so on. 1. Diabetic peripheral neuropathy. This disease is mainly caused by poor glycemic control and impaired peripheral nerve function, which can lead to numbness of the big toe. 2. Lumbar spine diseases. Including lumbar spinal stenosis, lumbar intervertebral disc herniation, etc., the onset of lumbar nerve root compression can lead to numbness in the big toe, accompanied by persistent dull pain in the lower back and other symptoms. Combined with lumbar spine CT and other examinations can be diagnosed. 3. Peripheral vascular disease. For example, when there is a blood clot in the lower limbs, due to insufficient blood supply to the lower limbs, the symptoms are manifested as numbness of the big toe. It can be diagnosed by Doppler examination of the blood vessels of the lower limbs and angiography. 4. Rheumatoid arthritis. At the onset of the disease, the patient may experience numbness of the big toe, accompanied by stiffness of the big toe and joint pain. There are other reasons for this disease, and it is recommended to find the cause and standardize the treatment under the guidance of a professional doctor.