Final answer:
Choosing a puncture site in the center of the finger pad is incorrect for self-monitoring blood glucose.
Step-by-step explanation:
The nurse identifies a need for additional teaching when the patient who is self-monitoring blood glucose chooses a puncture site in the center of the finger pad. The correct location for finger is on the sides of the finger pads, as the sides avoids stimulating the mechanoreceptors present in the center of the finger pad. Choosing the center of the finger pad increases the risk of nerve damage and can cause more pain. The other options, such as washing the puncture site using warm water and soap, hanging the arm down for a minute before puncturing the site, and a result of 120 mg indicating good blood sugar control, are all appropriate actions for self-monitoring blood glucose.