Causes. Numbness is usually caused by damage, irritation or compression of several nerves or a single branch of a nerve, most often situated in the periphery of your body. Diseases affecting the peripheral nerves, such as diabetes, also can cause numbness.Rarely, numbness can be caused by problems in your brain or spinal cord. Fortunately, numbness by itself is only rarely associated with potentially life-threatening disorders, such as strokes or tumors.Your doctor will need detailed information about your symptoms to diagnose the cause of your numbness.ortunately, numbness by itself is only rarely associated with potentially life-threatening disorders, such as strokes or tumors. Your doctor will need detailed information about your symptoms to diagnose the cause of your numbness.