Numbness in the left thumb is a relatively common phenomenon in daily life. The reasons for this are many and can be divided into the following points: 1. Mostly caused by prolonged maintenance of a posture, such as prolonged squatting in the patient’s daily life, resulting in poor blood circulation in the foot, leading to the appearance of temporary numbness. 2. 3, due to diabetes, if the long-term blood sugar control is relatively poor, it will easily lead to peripheral neuropathy and numbness.