During each visit, blood samples will be drawn frequently to measure glucose and other hormones. To make the blood sampling easier, a small tube, called a catheter, will be placed in a vein in the child's arm. A special cream may be used to numb the skin before the tube is placed. The tube will stay in the vein while the child is in the hospital. There may be some itching, stinging or pain from having the tube in the vein. However, there should be no pain when blood is drawn through the tube. If the tube stops working, a new one will need to be inserted.