This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Long term status of blood sugar is explained by:September 2008 \nSelect and explain. \nA. HbA, B. Serial measurement of FBS, C. Oral glucose tolerance test, D. HbA1c', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. D: HbA1cWhen plasma glucose is episodically elevated over time, small amounts of hemoglobin A are nonenzymatically glycated to form HbA1Careful control of the diabetes with insulin reduces the amount formed and consequently HbAIc concentration is measured clinically as an integrated index of diabetic control for the 4- to 6-week period before the measurement.', 'role': 'assistant'}]