Diabetic lancets are used to puncture the skin to get a blood sample that you test to determine how much glucose is in your blood. Lancet Devices hold the lancet. Lancets are made of sharp steel encased in hard plastic and come in various gauges. A higher gauge produces a smaller puncture and may be less painful. Some lancets are single use or are spring-loaded and pierce your skin without any help from you. Once your skin is punctured, you gently kneed the area to coax a drop of blood to the surface.