Final answer:
Exercise is a nonpharmacologic measure that can decrease the body's need for insulin in type 1 diabetes mellitus.
Step-by-step explanation:
The nurse teaches that exercise is a nonpharmacologic measure that will decrease the body's need for insulin in an adolescent newly diagnosed with type 1 diabetes mellitus. Regular physical activity can help improve insulin sensitivity and lower blood glucose levels, reducing the reliance on insulin medications. While adequate sleep and a low-stimulation environment can support overall health and well-being, they do not directly impact insulin needs. Similarly, a low-fat diet plays a role in managing diabetes but does not directly decrease the body's need for insulin.