At a glance

Also known as

Glycated serum protein; GSP; glycated albumin

Why get tested?

To help monitor your diabetes over time, especially when it is not possible to monitor using the HbA1c test. To help determine the effectiveness of changes to your diabetic treatment plan

When to get tested?

If you are diabetic and your doctor wants to measure your average blood glucose level over the last 2-3 weeks

Sample required?

A blood sample drawn from a vein in your arm or sometimes from a fingerstick

What is being tested?

The fructosamine test is a measurement of glycated protein. When glucose levels in the blood are elevated over a period of time, glucose molecules permanently combine with haemoglobin found inside the red blood cells (RBCs) and with albumin and other serum proteins - a process called glycation. The more glucose that is present, the greater the amount of glycated haemoglobin and glycated protein formed. These combined molecules persist for the life of the RBC or the protein and provide a record of the average amount of glucose that has been present in the blood over that time period. Since RBCs live for about 120 days, glycated haemoglobin (HbA1c) reveals average blood glucose levels over the past 2 to 3 months. Serum proteins have a shorter lifespan, about 14 to 21 days, so glycated proteins reflect average glucose levels over a 2 to 3 week time period.

Keeping blood glucose levels as close as possible to normal allows diabetic patients 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 and by occasional monitoring of the effectiveness of treatment using either a fructosamine or HbA1c test.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm or from a fingerstick.

The Test

How is it used?

Fructosamine testing has been available since the 1980s. Both fructosamine and HbA1c tests are used primarily as monitoring tools to help diabetics control their blood sugar (glucose), but HbA1c is much more popular and more widely accepted. Fructosamine may be useful in situations where the HbA1c cannot be reliably measured. Instances where fructosamine may be a better monitoring choice than HbA1c include:

  • Rapid changes in diabetes treatment - fructosamine allows the effectiveness of diet or medication adjustments to be evaluated after a couple of weeks rather than months
  • Diabetic pregnancy - good 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 and insulin requirements
  • RBC loss or abnormalities - an HbA1c test will not be accurate when a patient has a condition that affects the average age of red blood cells (RBCs) present, such as haemolytic anaemia or blood loss. The presence of some haemoglobin variants may affect certain methods for measuring HbA1c. In these cases, fructosamine can be used to monitor glucose control.

Since the fructosamine concentrations of well-controlled diabetics may overlap with those of non-diabetics, the fructosamine test is not useful as a screen for diabetes.

When is it requested?

Although not widely used, the fructosamine test may be ordered whenever the doctor wants to monitor a patient's average glucose over the past 2 to 3 weeks. It is primarily ordered when a diabetic treatment plan is being instituted or altered in order to monitor the effect of the change in diet or medication. Fructosamine levels also may be ordered when a diabetic patient is pregnant, or when they have an acute or systemic illness that may change their glucose and insulin requirements for a period of time. The fructosamine test may be used when monitoring is required and an HbA1c test cannot be reliably used.

What does the test result mean?

Looking for reference ranges?

If a patient's fructosamine is increased, then the patient's average glucose over the last 2 to 3 weeks has been elevated. In general, the higher the fructosamine concentration the higher the average blood glucose level. Trends may be more important that absolute values. If there is a trend from a normal to high fructosamine, it may indicate that a patient's glucose control is not adequate - that they are getting too much sugar, too little insulin, or that their insulin treatment has become less effective.

Normal fructosamine levels may indicate that a patient is either not diabetic (and therefore should not be monitored) or that he has good diabetic control. A trend from high to normal fructosamine levels may indicate that changes to a patient's treatment regimen are effective.

Fructosamine results must be evaluated in the context of the patient's total clinical findings. Falsely low fructosamine results may be seen with decreased protein levels, increased protein loss, or a change in the type of protein produced by the body. In this case, a discrepancy between the results obtained from daily glucose monitoring and fructosamine testing may be noticed. Also, someone whose glucose concentrations swing erratically from high to low may have normal or near normal fructosamine and HbA1c levels but still have a condition that requires frequent monitoring.

Common Questions

Do I need to fast for a fructosamine test?

No. Since it measures glycated protein and determines the average glucose over the past 2-3 weeks, the test is not affected by food that you have eaten during the day. For the same reason, fructosamine can be measured at any time during the day.

Should someone with a family history of diabetes have a fructosamine and an HbA1c test?

Not usually. These tests are not recommended for screening non-diabetic patients, even if you have a strong family history. One or more may be ordered, however, if you have an elevated fasting glucose.

Last Review Date: October 25, 2011