Numbness of the thumb may be caused by blood circulation disorders, peripheral neuritis, lumbar disc herniation, diabetic peripheral neuropathy and other reasons. 1. Blood circulation disorder: If the patient’s thumb is locally compressed, or suffers from varicose veins of the lower limbs, vasculitis and other diseases, it may lead to blood circulation disorders, resulting in numbness of the thumb. 2. Peripheral neuritis: If the patient is infected, poisoned or allergic, it may cause damage to the peripheral nerves, leading to peripheral neuritis, resulting in numbness and pain at the ends of the limbs. 3. Herniated lumbar intervertebral disc: If the patient suffers from herniated lumbar intervertebral disc, it may compress the nerve roots of the lower limbs, and the nerves of the lower limbs will become numb and weak, so the patient may feel numbness in the thumbs, insteps and lower limbs. 4. Diabetic peripheral neuropathy: If the patient suffers from diabetic peripheral neuropathy, the blood sugar will be relatively high, which will involve the peripheral nerves for a long time, causing peripheral nerve dysfunction, so the patient may experience sensory symptoms, such as numbness of the limbs, limb instability and so on. It is suggested that patients can play sports in their daily life and go to the hospital for regular medical checkups, and if they suffer from the disease, they should be treated as soon as possible.