Glossary term · Tests & reports
HbA1c test (also: A1C, Glycated haemoglobin, Haemoglobin A1c): The HbA1c test measures the percentage of haemoglobin coated with glucose, reflecting average blood sugar over about the past two to three months.
The HbA1c test shows your average blood sugar over roughly the past two to three months. MedlinePlus explains that glucose attaches to haemoglobin in red blood cells, which live about three months. The result is a percentage. Surgical teams may ask for an HbA1c result before planned surgery, especially if you have diabetes.
What is it used for?
- Screening for and diagnosing type 2 diabetes and prediabetes.
- Monitoring diabetes or prediabetes over time.
MedlinePlus says it is not used to diagnose type 1 or gestational diabetes, though it may help monitor type 1.
How are results described?
MedlinePlus gives below 5.7% as normal, 5.7% to 6.4% as prediabetes and 6.5% or higher as diabetes. Providers often confirm with another test.
What can affect accuracy?
- Conditions that affect red blood cells, such as anaemia.
- Kidney failure and liver disease.
- Some medicines, including opioids and some HIV medicines.
- Pregnancy.
Why does it matter before surgery?
Blood sugar control is part of the pre-operative work-up. If your HbA1c is high, the treating team may adjust your diabetes treatment before the procedure. They decide whether surgery should go ahead as planned.
Bring your diabetes plan
Bring your medicines, glucose meter and recent readings. Tell the team about fasting before tests and procedures.
Questions people ask
Do I need to fast for an HbA1c test?
MedlinePlus does not list fasting for the HbA1c test itself. It is often taken with other blood tests that may need fasting, so follow the laboratory’s instructions for the full set.
Can I travel for surgery with diabetes?
Talk to your own doctor first. The UK CAA advises discussing your travel itinerary with your doctor or diabetes team four to six weeks before travel. Your surgeon decides whether your diabetes control suits the planned operation.
Sources
General information, not medical or legal advice. Rules change: confirm with the official source. Your treating specialist decides on suitability, treatment and length of stay. How we write and check.