Final answer:
The next step after an adolescent with type 1 diabetes has learned about the disorder is to D) develop a meal plan with them, emphasizing the importance of understanding insulin usage and carbohydrate counting.
Step-by-step explanation:
Once a nurse determines that an adolescent with newly diagnosed type 1 diabetes has sufficient knowledge of the disorder, the next appropriate action is to develop a meal plan with the adolescent. Individuals with type 1 diabetes require consistent monitoring and management of their blood glucose levels, which includes insulin administration when blood sugar levels rise too high. It is also essential to have knowledge about carbohydrate counting to adjust insulin doses accordingly and manage blood sugar levels effectively.