Which test is used to assess long-term glucose control over the past 2-3 months?

Which test is used to assess long-term glucose control over the past 2-3 months?

• A. Fasting plasma glucose
• B. Oral glucose tolerance test
• C. HbA1c
• D. Random blood glucose

Answer: (C)

The test that best reflects long-term glucose control over the past 2–3 months is HbA1c. This measures the percentage of hemoglobin that has glucose attached to it, and because red blood cells live about 120 days, the HbA1c value provides an average blood glucose level over roughly the previous 2–3 months. It’s different from a single point-in-time reading, which is what fasting plasma glucose captures—a snapshot after an overnight fast. The oral glucose tolerance test assesses the body’s response to a glucose load and is used to diagnose diabetes or gestational diabetes, not to gauge long-term control. Random blood glucose is a casual measurement taken at any time and is influenced by recent meals and activity, so it doesn’t reflect overall control over months.

The test that best reflects long-term glucose control over the past 2–3 months is HbA1c. This measures the percentage of hemoglobin that has glucose attached to it, and because red blood cells live about 120 days, the HbA1c value provides an average blood glucose level over roughly the previous 2–3 months. It’s different from a single point-in-time reading, which is what fasting plasma glucose captures—a snapshot after an overnight fast. The oral glucose tolerance test assesses the body’s response to a glucose load and is used to diagnose diabetes or gestational diabetes, not to gauge long-term control. Random blood glucose is a casual measurement taken at any time and is influenced by recent meals and activity, so it doesn’t reflect overall control over months.