Fructosamine

Fructosamine from serum is a marker for diabetes, it is an earlier marker than HbA1c.
This test is also used when the HbA1c is not reliable enough because of anemia.

If anemia is suspected to affect HbA1c results, a fructosamine test can be ordered. the use of the fructosamine test is recommended in patients with conditions that affect red blood cell longevity, such as anemia.

Fructosamine is formed from sugar in the blood that attaches to a protein in the blood. Unlike hemoglobin, albumin and these other blood proteins that form fructosamine are not affected by anemia because they are not part of red blood cells. Like the A1C test, the more sugar in the blood, the more sugar attaches to albumin and other blood proteins to form fructosamine. Unlike the A1C test, the fructosamine test measures average blood sugar levels over the past three weeks rather than the past three months. This is because albumin has a shorter life span than hemoglobin.