An HbA1c test may be arranged for a diabetes check or monitoring. If you are booking one in Clapham or SW11, this guide covers fasting, the sample and questions to ask. It is general information, not an interpretation of your result.
What does HbA1c measure?
HbA1c (glycated haemoglobin) reflects glucose attached to haemoglobin in red blood cells. It indicates average blood glucose over roughly the previous two to three months, unlike a finger-prick reading, which is a snapshot. In practical terms, it gives a longer-term picture rather than a record of what you ate that morning. It can support diabetes checks and monitoring, but a clinician should interpret it in context. The NHS explains the test and sample process in its patient information.
Do I need to fast?
For HbA1c alone, fasting and special preparation are not normally required, as noted in NICE guidance. However, other tests taken at the same appointment may have different instructions. If your booking mentions several blood tests, ask whether any preparation applies to the whole appointment. Follow the advice given when your test is booked; if unsure, ask the clinic before changing meals or routine. Do not stop prescribed medication unless a healthcare professional advises you to.
What happens at the appointment?
A blood sample is taken for testing. Tell the person taking it if you are anxious or have fainted during a blood test before. Ask how and when you will receive the result and who will explain it. If the test was suggested at an earlier consultation, bring any booking or referral details you were given. You do not need to interpret the number on your own.
How should I understand the result?
NICE guidance uses an HbA1c of 48 mmol/mol or above as a diabetes threshold in adults in the appropriate clinical context. A result of 42–47 mmol/mol may indicate raised risk, called non-diabetic hyperglycaemia. These figures are not a self-diagnosis: if someone has no symptoms, NICE says one abnormal result alone should not establish a diagnosis; repeat testing is generally arranged to confirm it. Results are commonly written in mmol/mol; discuss anything unclear with a clinician rather than relying on generic online targets. A clinician can explain whether follow-up is needed.
Tell the clinician about relevant health factors
HbA1c may be unsuitable or harder to interpret in some circumstances, including pregnancy, recent childbirth, certain blood disorders or a recent transfusion. NICE advises against using it for diagnosis in some groups and recommends caution when red-cell turnover or haemoglobin is abnormal. Mention relevant conditions when arranging the test so a clinician can decide whether another approach is appropriate. Also mention medicines or recent illness if asked, as these may be relevant to interpretation.
Arrange an HbA1c test in Clapham
SW11 Clinic lists a Diabetes HbA1c test among its diagnostics. To ask about an appointment, contact the clinic or call 020 7223 5114.
This article is general information only; it cannot replace professional advice or diagnose an individual.