Fructosamine
Note: this site is for informational purposes only. To view test results or book a test, use the NHS app in England or contact your GP.
The fructosamine test measures your average blood glucose (sugar) level over the past two to three weeks. It is used to monitor diabetes when the standard HbA1c test cannot be reliably measured. It is a monitoring test, not a way to diagnose diabetes.
Who needs this test
The fructosamine test is not routinely used to manage diabetes. The HbA1c test is the standard way to monitor blood glucose control over the longer term, and it is used in the vast majority of cases. HbA1c can also be used to screen for and diagnose diabetes, whereas fructoasmine cannot.
Your doctor may request a fructosamine test in specific situations where HbA1c cannot be reliably measured or interpreted. These include:
- Certain inherited haemoglobin variants (such as sickle cell trait or thalassaemia) that affect some HbA1c testing methods
- Haemolytic anaemia or other conditions that affect how long your red blood cells live – these make HbA1c unreliable, and fructosamine can be used instead
- When a recent change to your diabetes treatment has been made and your doctor wants to see the effect sooner than HbA1c would allow
Fructoasmine is not used to diagnose diabetes. It is not recommended as a screening test for people without diabetes, even if you have a family history of the condition.
Preparing for your test
No preparation is needed. You do not need to fast before a fructosamine test. Because the test measures average glucose levels over the past two to three weeks, what you eat or drink on the day does not affect the result.
A blood sample is taken from a vein in your arm. This is the same as a routine blood test.
Understanding your results
What the test measures
When glucose levels in your blood are high for a period of time, glucose molecules attach themselves to proteins. This process is called glycation. The fructosamine test measures the amount of glycated protein in your blood – mainly albumin, the main protein in the blood.
Albumin and other blood proteins live for about 14 to 21 days. Because of this, the fructosamine level reflects your average blood glucose over roughly the past two to three weeks. This is a shorter window than HbA1c, which reflects blood glucose of the past two to three months.
The higher your average glucose has been over those weeks, the higher your fructosamine level is likely to be.
Fructosamine measurement is not standardised across laboratories. This means that results from different labs cannot be directly compared, and there are no universally agreed normal ranges or targets. Your doctor will interpret your result in the context of your individual situation, your other test results, and any trends over time. A single result is less meaningful than a pattern of results from the same laboratory.
What your results mean
If your fructosamine is raised
A raised fructosamine level suggests your average blood glucose has been higher than usual over the past two to three weeks. This may mean your diabetes has not been as well controlled during that period.
Your doctor will look at your fructosamine result alongside your day-to-day glucose readings and any recent changes to your diet or medication. Together, these give a fuller picture of your glucose control.
If your fructosamine appears normal despite high glucose readings
Fructosamine results can appear misleadingly low if your albumin or total protein levels are reduced. This can happen with conditions that cause protein loss, such as kidney disease or liver disease, or in certain other circumstances. Some laboratories therefore ‘correct’ or adjust fructoasmine results using measurements of total protein level.
If your day-to-day glucose readings are consistently high but your fructosamine appears normal, your doctor will consider whether a low protein level may be affecting the result. They may request an albumin or total protein test to check this.
Erratic glucose levels – swinging between high and low – can also produce a normal fructosamine result even when your diabetes needs close monitoring. In this situation, your glucose diary or continuous glucose monitoring data gives your doctor more useful information.
Questions to ask your doctor
What happens next
Your doctor will use your fructosamine result alongside your other information – such as your glucose diary, continuous glucose monitor data, or finger-prick readings – to review how well your diabetes is being managed.
If your fructosamine is raised, your doctor may review your diabetes treatment plan. This might involve changes to your diet, physical activity, or medication. Because fructosamine reflects the past two to three weeks, the effect of any changes can be seen relatively quickly compared with HbA1c.
What can affect your results
Several factors can interfere with fructosamine results and make them less reliable:
- Low albumin or total protein levels, caused by conditions such as kidney disease, liver disease, or malnutrition – these can make fructosamine appear falsely low. Some laboratories may ‘correct’ or adjust results for this.
- High doses of vitamin C (ascorbic acid) supplements
- A lipaemic sample (blood that is very high in fat, for example shortly after a fatty meal). Although note that fasting is not required for this test.
- Haemolysis (breakdown of red blood cells in the blood sample, which can happen during collection)
Your laboratory will flag if a sample appears unsuitable for testing. If your result seems inconsistent with your glucose diary or other clinical information, your doctor will consider whether any of these factors may be relevant.
Other tests you might need
In most people with diabetes, the HbA1c test is the main tool for monitoring long-term blood glucose control and for diagnosing diabetes. Your doctor will usually prefer HbA1c unless there is a specific reason to use fructosamine instead.
Other tests that may be used alongside or instead of fructosamine include:
- HbA1c – the standard measure of blood glucose control over two to three months
- Finger-prick (capillary) glucose testing – shows your glucose level at a specific moment; the most widely used day-to-day monitoring tool
- Continuous glucose monitoring (CGM) – provides a continuous real-time picture of glucose levels throughout the day and night
- Albumin and total protein tests – to check whether low protein levels may be affecting your fructosamine result
About diabetes
Diabetes is a condition in which the body cannot regulate blood glucose effectively. Over time, persistently high blood glucose can damage blood vessels, nerves, kidneys, and eyes. Good blood glucose control significantly reduces the risk of these complications.
Find out more about diabetes and its management on the NHS website.