This marker measures the total amount of fructosamine (glycated protein) in the blood.

A normal fructosamine level may indicate good glucose control and that the current treatment plan is effective for the individual. Likewise, a trend from high to normal fructosamine levels may indicate that changes to the treatment regimen have been effective.

Glucose molecules will permanently combine with proteins in the blood in a process called glycation. These proteins include albumin, the principal protein in the fluid portion of blood (serum), as well as other serum proteins and hemoglobin, the major protein found inside red blood cells (RBCs). The more glucose that is present in the blood, the greater the amount of glycated proteins that are formed. These combined molecules persist for as long as the protein or RBC is present in the blood and provide a record of the average amount of glucose that has been present in the blood over that time period.

Since the lifespan of RBCs is about 120 days, glycated hemoglobin (hemoglobin A1c) represents a measurement of the average blood glucose level over the past 2 to 3 months. Serum proteins are present in the blood for a shorter time, about 14 to 21 days, so glycated proteins, and the fructosamine test, reflect average glucose levels over 2 to 3 weeks.

Keeping blood glucose levels as close as possible to normal helps individuals with diabetes to avoid many of the complications and progressive damage associated with elevated glucose levels. Good diabetic control is achieved and maintained by daily (or even more frequent) self-monitoring of glucose levels in people treated with insulin and by occasional monitoring of the effectiveness of treatment using the A1c test or the fructosamine test.