Blood draw
Fructosamine
Fructosamine; average glucose (2–3 weeks).
€ 26,00
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Sugar and metabolism · Blood
Fructosamine
A measure of the average blood sugar over 2 to 3 weeks; unlike for HbA1c, there are no fixed target values.
At a glance
- Measured in blood
- In 1 test panel
- No special preparation
Explanation
Fructosamine: what is measured?
Glucose in the blood slowly sticks to proteins. Fructosamine is the collective name for these sugar-coated (glycated) proteins in the blood, mainly glycated albumin. Because these proteins last about two to three weeks, fructosamine reflects the average sugar level over that period. Unlike a single glucose measurement, which only shows the moment of the blood draw, this is therefore an average over several weeks.
What can it detect?
- An average blood sugar that has been too high over the past 2 to 3 weeks
- The short-term effect of a change in diabetes treatment
Result
What does the result mean?
Fructosamine too high
A raised value means that the sugar level has been too high on average over the past two to three weeks. The higher the value, the higher the average blood sugar. With known diabetes, this may mean that the treatment or the dose needs adjusting. A raised value can also occur with a temporarily high blood sugar due to illness, due to a course of prednisone or other corticosteroids, or due to a period of eating a lot of sugary food.
Fructosamine too low
A low value usually means that the average blood sugar over the past weeks was low or normal. Note: fructosamine depends strongly on the amount of protein in the blood. With a low albumin, for example due to liver disease, kidney disease with protein loss or inflammation, the result is low without the blood sugar being low. A low value on its own therefore does not mean that blood sugar control is good.
After an abnormal result
With a raised value, the GP usually measures a fasting glucose and an HbA1c before drawing a conclusion. With known diabetes, the treatment is adjusted if needed and checked again after a few weeks. With a strikingly low value, the GP looks at the albumin and at liver and kidney function.
Reliability
How reliable is the test?
Fructosamine gives an average over two to three weeks; HbA1c does so over about six to eight weeks. For HbA1c, the meaning and the target values have been well studied and are set out in the Dutch GP guideline (NHG) on type 2 diabetes mellitus; for fructosamine there are no agreed target or cutoff values. Fructosamine is mainly informative when HbA1c is unreliable because the red blood cells live shorter, for example with some blood diseases, with an abnormal form of hemoglobin, after bleeding or a transfusion and during pregnancy. Fructosamine has not been studied for, and is not suitable for, determining whether someone has diabetes.
What can affect the result?
- The result depends strongly on the protein concentration in the blood: with a low albumin it comes out too low, with a high albumin too high.
- A rapid change in blood sugar over the last few days is not yet visible; the value lags two to three weeks behind.
- There are no Dutch target or cutoff values; reference values differ per laboratory and between people with and without diabetes.
- High vitamin C intake, a strongly raised bilirubin and strongly raised blood fat levels can disturb the measurement.
Who it is for
Who is the test useful for?
Useful for
The test can be useful in people with diabetes in whom HbA1c does not give a reliable picture, for example with a shortened lifespan of the red blood cells, an abnormal form of hemoglobin, after bleeding or a transfusion and during pregnancy. It can also show the effect of a recent change in treatment sooner than HbA1c. In people without diabetes and without symptoms, the result says little: for diagnosing diabetes, a fasting glucose and HbA1c are the studied measures.
How common is it?
In the Netherlands about 1.2 million people have diabetes, by far most often type 2, and the number rises with age. How often an abnormal fructosamine occurs is not registered.
The NHG guideline on type 2 diabetes mellitus and Thuisarts.nl; the number of people with diabetes is a rounded estimate
Drawbacks and risks
- A low value due to a low albumin can make blood sugar control wrongly seem reassuring.
- Because Dutch target values are lacking, a slightly abnormal result is hard to interpret and can cause unnecessary worry.
Get tested
Fructosamine: test panels
Fructosamine is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.
Evidence
Sources
This explanation is based on Dutch guidelines and independent information. It is general information, not a diagnosis. Discuss an abnormal result with your GP.
More about risks and results