Hemoglobin is a protein that transports oxygen in red blood cells. Sugar, or glucose, slowly binds to the haemoglobin molecules in red blood cells. The amount of binding glucose depends on the glucose in the blood. The more sugar there is in the blood, the more binds to haemoglobin. This combination is called haemoglobin A1c (B-HbA1c).
Red blood cells live for approximately 2–3 months. Therefore, the HbA1c test indicates the average sugar balance in the body during the past 2–8 weeks. Because glucose binds slowly, momentary high or low glucose concentrations do not have an effect on HbA1c.
When should HbA1c be measured?
The HbA1c test is often taken in monitoring sugar balance in diagnosed type 2 diabetes. The test can also be used for diagnosing type 2 diabetes.
HbA1c should be checked when the following symptoms emerge:
- Weight loss
- High amounts of urine
- Dehydration of the body
- Increased thirst
- Irritability and melancholy
- Leg pain or sensory changes
- Impaired vision
What does a HbA1c test measure?
HbA1c, or glycosylated haemoglobin, indicates long-term blood sugar levels. The higher the level of long-term blood sugar, the more blood sugar, or glucose, binds to the haemoglobin in circulating red blood cells. The glycosylated haemoglobin HbA1c test is used for diagnosing and monitoring diabetes.
How to interpret the HbA1c test result?
Normally, the result is:
Reference values: 20–42 mmol/mol
Lower red blood cell life, such as when the breaking down of red blood cells is accelerated because of a disease, causes incorrectly low HbA1c results.
Assessing the control of diabetes:
- good sugar balance HbA1c below 53 mmol/mol (under 7%)
- reasonably good sugar balance HbA1c below 53–75 mmol/mol (7–9%)
- poor sugar balance HbA1c over 75 mmol/mol (over 9%)
Incorrectly high or low HbA1c values can be caused by factors affecting the life of red blood cells and haemoglobin. The HbA1c test is not used for diagnosing diabetes during pregnancy.
When the body sugar balance is restored, the HbA1c level begins to decrease within approximately 10–20 days.
Read more about defining reference values.
Please contact your physician or other healthcare professional if you suspect an illness or need help interpreting the results.
What can cause elevated HbA1c values?
Elevated HbA1c levels can be seen in the following situations:
- Diabetes is not under control
- Blood sugar level is high
- Iron deficiency anaemia
- After a splenectomy, because red blood cells live longer
In diabetes patients, a high HbA1c level increases the risk of associated diseases. A long-term excessive body sugar level damages the nervous system, veins, eyes, kidneys, legs, and mouth, among other things.
What can cause decreased HbA1c values?
Decreased HbA1c values can occur due to increased breakdown of red blood cells (haemolytic anaemias). In this case, the life of the red blood cells is short, and this has a lowering effect on the HbA1c result. The level can also be decreased by bleeding and abundant red blood cell transfusions.
The most typical additional HbA1c tests:
- Blood sugar gives the body energy (1468 fP-Gluk)
SYNLAB test list: Haemoglobin-A1c (6128 B-HbA1c) https://www2.synlab.fi/laboratoriokasikirja/tutkimuskuvaukset/hemoglobiini-a1c-6128-b-hba1c/
Terveyskirjasto health library: Hemoglobiini HbA1c (B-HbA1c) https://www.terveyskirjasto.fi/terveyskirjasto/tk.koti?p_artikkeli=snk03092&p_hakusana=HbA1c
Diabetes: HbA1c mittaa punasolujen sokeroitumista https://diabeteslehti.diabetes.fi/blog/2016/08/19/hba1c-koe-mittaa-punasolujen-sokeroitumista/
Terveyskylä: Sokerihemoglobiini HbA1c https://www.terveyskyla.fi/diabetestalo/tietoa/diabeteksen-seuranta/verensokeritasapainon-seuranta/sokerihemoglobiini-hba1c#
Lab Test online: HbA1c test https://labtestsonline.org.uk/tests/hba1c-test
Fasting is not required
This examination does not require fasting