1. Another Average Blood Glucose Indicator: Fructosamine
Fructosamine, like hemoglobin A1c, is a substance formed when glucose in the blood binds to proteins. While HbA1c is glucose bound to the ‘hemoglobin’ protein in red blood cells, fructosamine is primarily glucose bound to ‘albumin,’ the most abundant protein in blood serum.
2. The Difference in the Reflection Period
The biggest difference between the two tests is the ‘period’ of average blood sugar they reflect. This period is determined by the average lifespan of the protein to which the glucose attaches.
– Hemoglobin A1c (HbA1c): Since the average lifespan of a red blood cell containing hemoglobin is about 3-4 months, HbA1c reflects the average blood sugar over the past **2-3 months**.
– Fructosamine: The average lifespan of albumin is much shorter than that of red blood cells, only about 20 days. Therefore, the fructosamine level reflects the short-term average blood sugar over the past **2-3 weeks**.
3. When is the Fructosamine Test Used?
Due to this characteristic, the fructosamine test is useful in specific situations:
– Observing Short-Term Changes: It is used when a doctor wants to quickly see the effects of a change in diabetes medication or insulin dosage within 2-3 weeks. For HbA1c, one would have to wait 2-3 months.
– When HbA1c is Inaccurate: It can be used as an alternative when the HbA1c test result is unreliable due to conditions that affect the lifespan of red blood cells, such as pregnancy or hemolytic anemia.
Summary: Because of the short lifespan of albumin, the fructosamine test reflects the average blood sugar over a much shorter period of about 2-3 weeks compared to HbA1c. While HbA1c is the standard for long-term management, fructosamine can be more useful for observing short-term changes.
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