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NOTE:
unless noted otherwise, all medical/health advice has been given by non-medically qualified personnel. All advice given on this site is designed to support and not replace any advice given by your personal physician. If you have questions or concerns about individual health matters or the management of your diabetes, please consult your diabetes care team.
unless noted otherwise, all medical/health advice has been given by non-medically qualified personnel. All advice given on this site is designed to support and not replace any advice given by your personal physician. If you have questions or concerns about individual health matters or the management of your diabetes, please consult your diabetes care team.
As part of your check-up, your doctor will usually take blood for a number
of tests including the HbA1c or "glycated haemoglobin" test. But what is it
and what do the results mean?
Depending on the laboratory that does your test, it might be called any of the following:
Glycated haemoglobin
You have probably already heard of haemoglobin - it's the red pigment in the blood that carries oxygen round the body. Glycated haemoglobin (HbA1 or HbA1c) is haemoglobin with extra glucose molecules that have attached to it.
How is it formed?
Haemoglobin is found inside red blood cells (in fact, it is the haemoglobin that makes the blood red). Glucose in the blood attaches itself to haemoglobin naturally to form glycated haemoglobin.
The amount of glycated haemoglobin that forms depends on the level of glucose in the blood. So, if the blood glucose level is high, more glycated haemoglobin, or HbA1c, is formed.
Glucose molecules take a while to attach themselves securely to haemoglobin. So, if the blood glucose level is only high for a short period of time (a couple of hours, say) some glucose molecules will not have attached permanently and less glycated haemoglobin is formed.
Everyone has some glycated haemoglobin in their blood, but people with diabetes tend to have higher levels.
What does the test tell you?
The amount of haemoglobin that has glucose permanently attached to it gives an indication of the 'average' blood glucose level over the previous few weeks. If your diabetes has not been well controlled and blood glucose levels have been higher than normal for extended periods of time, then this will be reflected in a high HbA1c result.
Red blood cells are continually being replaced in the body. Old ones are broken down and new ones are made in the bone marrow. The average lifetime of a red blood cell is about 120 days. This means that haemoglobin has approximately 120 days to collect glucose molecules on it, before it is destroyed and replaced with new haemoglobin.
What do the results mean?
The results of the test are given as a percentage. This is the percentage of haemoglobin that has been glycated.
People who do not have diabetes generally have an HbA1c level of less than 6 %. This means that less than 6 % of their haemoglobin molecules have glucose permanently attached.
The HbA1c level in people who have diabetes gives a good indication of how well their blood glucose has been controlled during the previous 2 - 3 months.
NOTE! It is purely coincidence that this 'normal' reference figure of 6 % lies mid-way between the normal range of blood glucose levels (4 - 8 mmol/ l). Whilst the HbA1c does give an indication of the average blood glucose level, it is not a direct relationship.
Why do I need to have an HbA1c blood test?
Your daily blood glucose tests provide only a snapshot of glycaemic control at the moment you test. The HbA1c test, on the other hand, gives you the big picture by showing how your blood glucose control has been over the previous couple of months. You could think of it as a kind of batting average if you like.
HbA1c tests are helpful to your doctor because they give an immediate indication of your blood glucose control. (It is certainly easier than ploughing through the last three month's worth of your diabetes diary!)
Over a longer period of time, consecutive HbA1c tests will provide an overall trend in your diabetes control. If your HbA1c is progressively rising each time you visit the clinic then it may suggest that your treatment plan needs modifying. (If you have Type 2 diabetes, then perhaps you need to start taking tablets, or insulin, for example.)
Finally, HbA1c tests are often used in setting and achieving treatment goals.
How can the HbA1c help me to manage my diabetes?
If you do not test your blood glucose level very often, then you might not have a very clear picture of what is happening throughout the day. It may be that your tests are always in the normal range, yet your HbA1c level comes back much higher than expected. This would indicate that your blood glucose level is actually rising at some stage(s) through the day. Perhaps you are just testing first thing in the morning, or just before meals. It is quite possible that your blood glucose level is rising too high after meals, but you are not aware of this. So, the HbA1c test gives you more clues as to what's really going on.
If your HbA1c level comes as something of a surprise, or if it is particularly high, then you may benefit from doing more frequent blood glucose testing. This should help to show you and your healthcare team where improvements could be made to your treatment plan.
The HbA1c test may also help to motivate you. If your levels are progressively increasing then you may be alerted to the fact that you have been letting your control slip recently. If your levels are slowly improving then you should give yourself a pat on the back!
So what HbA1c level should I be aiming for?
There are no hard and fast answers to this question. Your target HbA1c or glycated haemoglobin level will depend on a number of factors and you should discuss this with your doctor. It will also depend on the reference range supplied by the laboratory that performs the test (see below).
Important note:
Currently there is no standard for HbA1c measurement in laboratories. This means that different laboratories use different methods and quote slightly different reference ranges. Some laboratories measure HbA1 or Gly Hb, which give higher values than HbA1c.
Find out which method your laboratory uses and what the reference range is.
As a very general guide:
For HbA1c: Target level of less than 7.0 % indicates good control (Laboratory normal range 4.0 - 6.0 %)
For HbA1: Target level of less than 8.8% indicates good control (Laboratory normal range 5.0 - 7.5 %)
Fructosamine Test
There is another type of test that gives an indication of blood glucose control over the previous 2 - 3 weeks. This is called the Fructosamine test. It is based on the same principle as the glycated haemoglobin test, but plasma proteins with glucose attached are measured, as opposed to haemoglobin. (Plasma proteins are proteins floating freely in the liquid portion of the blood)
Some people refer to Fructosamine as GSP or glycated serum protein.
The amount of glucose that attaches itself to the plasma proteins to form Fructosamine depends on the level of glucose in the blood and the length of time that it is at that level. Because plasma proteins have a shorter lifespan, compared to haemoglobin in red blood cells, Fructosamine gives an indication of blood glucose control over a much shorter period of time.
Fructosamine levels are useful in the short-term, for example:
Depending on the laboratory that does your test, it might be called any of the following:
- HbA1c
- HbA1
- Gly Hb
Glycated haemoglobin
You have probably already heard of haemoglobin - it's the red pigment in the blood that carries oxygen round the body. Glycated haemoglobin (HbA1 or HbA1c) is haemoglobin with extra glucose molecules that have attached to it.
How is it formed?
Haemoglobin is found inside red blood cells (in fact, it is the haemoglobin that makes the blood red). Glucose in the blood attaches itself to haemoglobin naturally to form glycated haemoglobin.
The amount of glycated haemoglobin that forms depends on the level of glucose in the blood. So, if the blood glucose level is high, more glycated haemoglobin, or HbA1c, is formed.
Glucose molecules take a while to attach themselves securely to haemoglobin. So, if the blood glucose level is only high for a short period of time (a couple of hours, say) some glucose molecules will not have attached permanently and less glycated haemoglobin is formed.
Everyone has some glycated haemoglobin in their blood, but people with diabetes tend to have higher levels.
What does the test tell you?
The amount of haemoglobin that has glucose permanently attached to it gives an indication of the 'average' blood glucose level over the previous few weeks. If your diabetes has not been well controlled and blood glucose levels have been higher than normal for extended periods of time, then this will be reflected in a high HbA1c result.
Red blood cells are continually being replaced in the body. Old ones are broken down and new ones are made in the bone marrow. The average lifetime of a red blood cell is about 120 days. This means that haemoglobin has approximately 120 days to collect glucose molecules on it, before it is destroyed and replaced with new haemoglobin.
What do the results mean?
The results of the test are given as a percentage. This is the percentage of haemoglobin that has been glycated.
People who do not have diabetes generally have an HbA1c level of less than 6 %. This means that less than 6 % of their haemoglobin molecules have glucose permanently attached.
The HbA1c level in people who have diabetes gives a good indication of how well their blood glucose has been controlled during the previous 2 - 3 months.
NOTE! It is purely coincidence that this 'normal' reference figure of 6 % lies mid-way between the normal range of blood glucose levels (4 - 8 mmol/ l). Whilst the HbA1c does give an indication of the average blood glucose level, it is not a direct relationship.
Why do I need to have an HbA1c blood test?
Your daily blood glucose tests provide only a snapshot of glycaemic control at the moment you test. The HbA1c test, on the other hand, gives you the big picture by showing how your blood glucose control has been over the previous couple of months. You could think of it as a kind of batting average if you like.
HbA1c tests are helpful to your doctor because they give an immediate indication of your blood glucose control. (It is certainly easier than ploughing through the last three month's worth of your diabetes diary!)
Over a longer period of time, consecutive HbA1c tests will provide an overall trend in your diabetes control. If your HbA1c is progressively rising each time you visit the clinic then it may suggest that your treatment plan needs modifying. (If you have Type 2 diabetes, then perhaps you need to start taking tablets, or insulin, for example.)
Finally, HbA1c tests are often used in setting and achieving treatment goals.
How can the HbA1c help me to manage my diabetes?
If you do not test your blood glucose level very often, then you might not have a very clear picture of what is happening throughout the day. It may be that your tests are always in the normal range, yet your HbA1c level comes back much higher than expected. This would indicate that your blood glucose level is actually rising at some stage(s) through the day. Perhaps you are just testing first thing in the morning, or just before meals. It is quite possible that your blood glucose level is rising too high after meals, but you are not aware of this. So, the HbA1c test gives you more clues as to what's really going on.
If your HbA1c level comes as something of a surprise, or if it is particularly high, then you may benefit from doing more frequent blood glucose testing. This should help to show you and your healthcare team where improvements could be made to your treatment plan.
The HbA1c test may also help to motivate you. If your levels are progressively increasing then you may be alerted to the fact that you have been letting your control slip recently. If your levels are slowly improving then you should give yourself a pat on the back!
So what HbA1c level should I be aiming for?
There are no hard and fast answers to this question. Your target HbA1c or glycated haemoglobin level will depend on a number of factors and you should discuss this with your doctor. It will also depend on the reference range supplied by the laboratory that performs the test (see below).
Important note:
Currently there is no standard for HbA1c measurement in laboratories. This means that different laboratories use different methods and quote slightly different reference ranges. Some laboratories measure HbA1 or Gly Hb, which give higher values than HbA1c.
Find out which method your laboratory uses and what the reference range is.
As a very general guide:
For HbA1c: Target level of less than 7.0 % indicates good control (Laboratory normal range 4.0 - 6.0 %)
For HbA1: Target level of less than 8.8% indicates good control (Laboratory normal range 5.0 - 7.5 %)
Fructosamine Test
There is another type of test that gives an indication of blood glucose control over the previous 2 - 3 weeks. This is called the Fructosamine test. It is based on the same principle as the glycated haemoglobin test, but plasma proteins with glucose attached are measured, as opposed to haemoglobin. (Plasma proteins are proteins floating freely in the liquid portion of the blood)
Some people refer to Fructosamine as GSP or glycated serum protein.
The amount of glucose that attaches itself to the plasma proteins to form Fructosamine depends on the level of glucose in the blood and the length of time that it is at that level. Because plasma proteins have a shorter lifespan, compared to haemoglobin in red blood cells, Fructosamine gives an indication of blood glucose control over a much shorter period of time.
Fructosamine levels are useful in the short-term, for example:
- In assessing the effects of changing a treatment plan
- During pregnancy, when treatment needs can change drastically and good control is vital
