Fasting Required: No

Specimen: Blood

Lab: Quest Diagnostics

Results: 3-5 business days
Note: Result turnaround times are an estimate and are not guaranteed. Our reference lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance.

Limitations: Patients with low albumin concentrations may exhibit depressed levels of fructosamine.

Description: Reflects average glucose levels over a 2 to 3 week time period.
If someone's fructosamine is increased, then their average glucose over the previous 2 to 3 weeks has been elevated. In general, the higher the fructosamine concentration, the higher the average blood glucose level. High levels of vitamin C (ascorbic acid) and hyperthyroidism can interfere with test results.

Both fructosamine and A1C tests are used primarily as monitoring tools to help people with diabetes control their blood sugar. However, the A1C test is much more popular and much more widely accepted because there are firm data that a chronically elevated A1c level predicts an increased risk for certain diabetic complications, such as retinopathy (possibly leading to blindness), nephropathy (possibly leading to kidney failure), and neuropathy (e.g., problems with the nerves). The American Diabetes Association (ADA) recognizes both tests and states that fructosamine may be useful in situations where A1C cannot be reliably measured.

Instances where fructosamine may be a better monitoring choice than A1C include:

Rapid changes in diabetes treatment – Fructosamine allows the effectiveness of diet or medication adjustments to be evaluated after a few weeks rather than months.

Diabetic pregnancy – In diabetic women who are pregnant, good glycemic control is essential during pregnancy, and the needs of the mother frequently change during gestation; fructosamine measurements may be ordered along with glucose levels to help monitor and accommodate shifting glucose, insulin, or other medication requirements.

Shortened RBC life span – An A1C test will not be accurate when a person has a condition that affects the average life span of red blood cells (RBCs), such as hemolytic anemia or blood loss. If the RBCs don't live as long as normal in the circulation, the A1c result will be falsely lowered and will be an unreliable measurement of a person's average glucose.

Abnormal forms of hemoglobin – The presence of some hemoglobin variants (such as sickle hemoglobin) may affect certain methods for measuring A1c. In these cases, fructosamine can be used to monitor glucose control.

Since the fructosamine concentrations of people with well-controlled diabetes may overlap with those of people who are not diabetic, the fructosamine test is not useful as a screening test for diabetes.

Alternative Name(s): Glycated Serum Protein, GSP