Final answer:
The client's statement should demonstrate an understanding of the purpose and significance of the HbA1c test.
Step-by-step explanation:
To indicate that education has been effective, the client should make a statement that demonstrates an understanding of the purpose and significance of the HbA1c test. For example, the client could say, "The HbA1c test measures my average blood glucose level over the past 4 months and helps determine how well my diabetes is being controlled." This statement shows that the client understands that the test reflects long-term blood glucose control and is an important tool in managing diabetes.