What does "fasting blood glucose" measure?

Fasting blood glucose measures the level of sugar (glucose) in a person's blood after they have not eaten for at least 8 hours. This test is vital for diagnosing diabetes or prediabetes, as it provides a clear indication of how well the body manages glucose without the influence of recent food intake.

When a person fasts, their body uses stored glucose for energy, and the fasting blood glucose level reflects the balance between the amount of glucose produced by the liver and the body's insulin response. The measurement is taken in a controlled setting to ensure accuracy, as food consumption can markedly elevate blood sugar levels, thus making it difficult to assess how well the body is regulating glucose over time.

The other options focus on unrelated measurements: blood pressure or cholesterol following food intake and iron levels after blood donation do not pertain to fasting blood glucose. These distinctions highlight the specific purpose of the fasting blood glucose test within the broader context of metabolic health assessments.