The symptoms of hypoglycemia primarily manifest as signs of sympathetic nervous excitement and lack of oxygen in brain cells. Sympathetic nervous excitement can cause feelings of hunger, pale complexion, palpitations, dizziness, and trembling limbs. Meanwhile, the lack of oxygen in brain cells primarily presents as disturbances in neurological functions. The most common symptoms include inability to concentrate, slow speech and thought processes, drowsiness, abnormal behavior, and in severe cases, it can even lead to coma.