A male patient who has a history of type 2 DM is admitted to the medical unit with a diagnosis of pneumonia. The patient has many Questions regarding his care and asks the nurse why everyone keeps telling him about HbA1C. What can the nurse inform the patient about the use of HbA1C in diabetes mellitus?

Choice A rationale The HbA1c test measures the average blood glucose concentration over the past two to three months by assessing the amount of glycated hemoglobin in red blood cells. It does not differentiate between type 1 or type 2 diabetes mellitus, as both conditions can result in elevated blood glucose levels and thus an elevated HbA1c reading. A diagnosis of type 1 versus type 2 diabetes requires a different diagnostic approach. Choice B rationale The HbA1c test measures the percentage of hemoglobin with glucose molecules attached. This is an indicator of long-term average blood glucose control and is not a marker for infection. Infections can cause an acute increase in blood glucose levels but do not directly or immediately affect the HbA1c, which reflects a longer-term trend. The normal HbA1c is below 5.7%. Choice C rationale Glycated hemoglobin forms when hemoglobin in red blood cells binds to glucose in the bloodstream. Since red blood cells have a lifespan of approximately 120 days, the HbA1c level reflects the average blood glucose concentration over the preceding two to three months. This provides a valuable metric for assessing patient adherence to diet, exercise, and medication regimens over an extended period. Choice D rationale The HbA1c value represents the average blood glucose level over a two to three month period, not the patient’s current or fasting blood glucose level. A fasting blood glucose test measures the glucose concentration in the blood at a single point in time, specifically after at least eight hours of not eating. These two tests provide different snapshots of glycemic control.