Formal name: Fructosamine
What is being tested?
Fructosamine is a compound that is formed when glucose combines with protein. The fructosamine test is a measurement of this glycated protein (this is an advanced glycation endproduct, or AGE). When glucose levels in the blood are elevated over a period of time, glucose molecules permanently combine with proteins in the blood in a process called glycation. Affected proteins include albumin, the principal protein in the blood, 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 the life of the protein or RBC 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 hemoglobin (HbA1c) represents a measurement of the average blood glucose level over the past 2 to 3 months. Serum proteins have a shorter lifespan, about 14 to 21 days, so glycated proteins, and the fructosamine test, reflect average glucose levels over a 2 to 3 week time period.
Keeping blood glucose levels as close as possible to normal helps those 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 insulin-treated diabetics and by occasional monitoring of the effectiveness of treatment using either a fructosamine or A1C test.
How is it used?
A blood sample is obtained by inserting a needle into a vein in the arm or from a fingerstick. Fructosamine testing has been available since the 1980s. Both fructosamine and HbA1c tests are used primarily as monitoring tools to help people with diabetes control their blood sugar. However, the HbA1c 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 measured reliably.
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 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.
When is it ordered?
Although not widely used, the fructosamine test may be ordered whenever the doctor wants to monitor a person’s average glucose levels over the past 2 to 3 weeks. It is primarily ordered when a diabetic treatment plan is being started or adjusted in order to monitor the effect of the change in diet, exercise, or medication.
Fructosamine levels also may be ordered periodically when a diabetic woman is pregnant or when a person has 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 A1C test cannot be reliably used, as in cases of a shortened RBC life span or in some cases where the person being tested has an abnormal hemoglobin.
Reference values are dependent on many factors, including patient age, gender, sample population, and test method, and numeric test results can have different meanings in different labs. The lab report containing your test results should include the specific reference range for your test(s). Please consult your doctor or the lab that performed the test(s) to obtain the reference range if you do not have the lab report.
What does the test result mean?
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. Trends may be more important than absolute values. If there is a trend from a normal to a high fructosamine level, it may indicate that a person’s glucose control is not adequate – that they are getting too much sugar, too little medication, or that their medication has become less effective. Acute illness and significant stress can also temporarily raise blood glucose levels.
Normal fructosamine levels may indicate that a person is either not diabetic (and therefore should not be monitored) or that they have good diabetic control. A trend from high to normal fructosamine levels may indicate that changes to a person’s treatment regimen are effective.
Fructosamine results must be evaluated in the context of a person’s overall clinical findings. Falsely low fructosamine results may be seen with decreased blood total protein and/or albumin levels, with conditions associated with increased protein loss in the urine or gastrointestinal tract, or with changes 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. However, most people with such unstable diabetic control do have elevated fructosamine and HbA1c concentrations.
Can I test for fructosamine at home?
No. Although a home test was available in the past, it was discontinued in 2002 after the manufacturer was purchased by another company and amid concerns that the test strips were producing falsely high results.
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 fructosamine test is not affected by food that you have eaten during the day. It can be measured at any time during the day.
Shouldn’t someone with a family history of diabetes have a fructosamine test?
Not usually. This test is not recommended for screening non-diabetic people, even if you have a strong family history.
If I have diabetes, should I have a fructosamine test?
The vast majority of people with diabetes can be monitored using HbA1c tests that reflect their glycemic control over the previous 2 to 3 months. Fructosamine testing is only appropriate during pregnancy when the woman has diabetes, when a person’s RBCs have a shortened survival, and in some cases of people with abnormal hemoglobins.
We have not used this test primarily because our boy’s HbA1c results have been so stable. We have heard of others having this test done when a shorter period of time for unstable blood sugars may have been involved, when diet and lifestyle changes have been implemented, or when pregnant. It is good to know this test is available if, for any reason we need to know what has transpired over the last 2 to 3 weeks.
Mapping, monitoring and measuring are a continuous cycle when living with diabetes. You begin with a certain course of treatment in mind, which you mapped out with the help of your medical professional. You monitor your progress and measure it against your goals. Upon evaluation, you may find a new course must be corrected to compensate for successes and challenges. Evaluating progress and results of the Health-e-Solutions lifestyle is essential for mastering diabetes in the healthiest way possible. This downloadable printable e-publication equips you with the key evaluation tools you need, along with the research behind them, to determine where you want to go and how to get there. We give you important tools to help you chart your course and stay on track to reach your destination.