There are numerous causes for tingling in the left hand, and some include diabetes, vitamin deficiencies and systemic diseases. Other possible causes for tingling in hands and feet are alcoholism, toxins, infections, autoimmune disorders, inherited disorders and injuries, according to WebMD. A doctor can perform a variety of tests to determine the cause of tingling in the hands and feet.
Some of the tests that a doctor might perform to determine the cause of this problem include a nerve biopsy, skin biopsy, MRI or CT scan. Doctors can determine the best course of action for a treatment plan once a proper diagnosis has been made. At-home lifestyle changes can help decrease the cause of hand and feet tingling including consuming a balanced diet and regularly exercising.