When Monitoring a Patient's Response to Oral Antidiabetic Drugs, the Nurse

When monitoring a patient's response to oral antidiabetic drugs, the nurse knows that which laboratory result would indicate a therapeutic response?

A) Random blood glucose level above 170 mg/dL
B) Blood glucose level of less than 50 mg/dL after meals
C) Fasting blood glucose level between 70 and 100 mg/dL
D) Evening blood glucose level below 80 mg/dL