Final answer:
The nurse should identify decreased fasting blood glucose as the finding that indicates the medication has been effective in managing uncontrolled type 2 diabetes mellitus with insulin.
Step-by-step explanation:
The nurse should identify decreased fasting blood glucose as the finding that indicates the medication has been effective in managing uncontrolled type 2 diabetes mellitus with insulin. Insulin injections allow the transport and storage of glucose, decreasing blood glucose levels after consuming a meal. This helps regulate blood glucose levels and prevents hyperglycemia.