Final answer:
The correct action indicating an understanding of how to self-administer NPH insulin is wiping the cap with alcohol prior to injection. This practice maintains sterility and effectively manages blood sugar levels in individuals with type 1 diabetes.
Step-by-step explanation:
A client with type 1 diabetes mellitus who is learning to self-administer NPH insulin demonstrates an understanding of the teaching when they wipe the cap with alcohol prior to filling the syringe. This action ensures that the insulin remains sterile and reduces the risk of infection at the injection site. Proper technique for self-administration of insulin is crucial for people with diabetes to manage their blood sugar levels effectively. Injecting insulin helps to transport and store glucose, decreasing blood glucose levels after a meal, contrary to statement C which incorrectly suggests that it increases blood glucose levels. Today, human insulin can be obtained from pharmacists thanks to the development of recombinant DNA technology, providing a significant advantage over previous insulin sources.