How long does an HbA1c test take to come back? For most patients in the UK, results are typically available within 2 to 7 working days of the blood sample being taken, with many NHS GP practices returning results in 3 to 5 working days. In some specialist settings, point-of-care testing can deliver a result within minutes — though this cannot be used for diagnosis. This article explains what to expect from the HbA1c testing process, how results are interpreted using NICE thresholds, and what steps to take once your result arrives.

How Long Does an HbA1c Test Take to Come Back?

HbA1c results are typically available within 2–7 working days on the NHS, with most GP practices receiving them in 3–5 working days; point-of-care testing can return a result in 10–15 minutes but cannot be used for diagnosis.

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For most patients in the UK, HbA1c test results are typically available within 2 to 7 working days of the blood sample being taken. In many NHS GP practices, results are returned within 3 to 5 working days, though this can vary depending on the laboratory used and local service arrangements. These are general estimates; your GP surgery can advise on the expected turnaround time for your local laboratory.

In some settings — particularly hospital outpatient clinics or specialist diabetes services — point-of-care HbA1c testing may be available. These desktop analysers can produce a result within 10 to 15 minutes during the same appointment, which can be useful for monitoring purposes. However, point-of-care HbA1c testing should not be used to diagnose diabetes; UK guidance (NICE NG28) requires that diagnosis is based on a quality-assured laboratory venous blood sample. Point-of-care testing is also not universally available across all NHS sites.

It is worth noting that receiving the result and being contacted about it are two separate steps. Your GP surgery may ask you to book a follow-up appointment to discuss the findings, or they may contact you by phone, letter, or via an NHS-linked patient portal such as the NHS App. If you have not heard anything within 7 to 10 working days, it is reasonable to contact your surgery to enquire.

How the HbA1c Test Is Carried Out on the NHS

The HbA1c test uses a venous blood sample — no fasting required — and measures glycated haemoglobin to reflect average blood glucose over the preceding 2–3 months; results are reported in mmol/mol in line with NHS and IFCC standards.

The HbA1c (glycated haemoglobin) test measures the proportion of haemoglobin in your red blood cells that has glucose attached to it. Red blood cells have a lifespan of approximately 120 days (around 4 months); because glucose attaches to haemoglobin gradually and irreversibly throughout this period, the test provides a reliable picture of your average blood glucose levels over the preceding 2 to 3 months, with the most recent weeks contributing most to the result. This makes it far more informative than a single fasting glucose reading.

On the NHS, the test is performed using a venous blood sample, typically drawn from a vein in the arm by a GP, practice nurse, or phlebotomist. Unlike fasting glucose tests, no fasting is required before an HbA1c test, which makes it more convenient for patients. The sample is collected into a specific EDTA (purple-top) tube and sent to an accredited NHS laboratory for analysis using high-performance liquid chromatography (HPLC) or immunoassay methods.

HbA1c is reported in mmol/mol in the UK, in line with the International Federation of Clinical Chemistry (IFCC) standardisation adopted by the NHS. Some reports also display the older percentage value (NGSP/DCCT units) in parentheses for reference, and some patients may encounter both figures. Current NHS and NICE guidance uses mmol/mol as the primary unit. If you are unsure which unit your result is expressed in, your GP surgery can clarify this.

Factors That Can Affect How Quickly You Get Your Results

Turnaround time can be extended by laboratory workload, poor sample quality, bank holidays, or GP administrative delays; certain conditions such as haemoglobinopathies can also affect result reliability, requiring alternative diagnostic tests.

Several practical and clinical factors can influence how long it takes to receive your HbA1c result after the blood test:

• Laboratory workload and location: Samples sent to busy centralised NHS laboratories may take longer to process than those analysed at a local hospital site.

• Sample quality: If the blood sample is haemolysed (broken down), clotted, or insufficient in volume, the laboratory may need to request a repeat sample, adding several days to the process.

• Bank holidays and weekends: NHS laboratories typically operate on reduced staffing at weekends and are closed on public holidays, which can extend turnaround times.

• GP administrative processes: Even once a result is received by the surgery, it may take additional time for a clinician to review and act upon it before contacting the patient.

Certain medical conditions can also affect the reliability of the HbA1c result itself, though this does not necessarily delay the result. Conditions such as haemolytic anaemia, haemoglobinopathies (e.g., sickle cell disease or thalassaemia), iron deficiency anaemia, recent blood transfusions, or other conditions that alter red blood cell turnover can interfere with the accuracy of the test.

In these situations, HbA1c should not be used to diagnose diabetes. Instead, NICE NG28 recommends using a fasting plasma glucose test or a 75 g oral glucose tolerance test (OGTT) for diagnostic purposes. For ongoing monitoring in people already diagnosed with diabetes, your clinician may consider alternatives such as fructosamine measurement or continuous glucose monitoring (CGM), depending on your individual circumstances.

Understanding Your HbA1c Result and What It Means

An HbA1c below 42 mmol/mol is normal, 42–47 mmol/mol indicates non-diabetic hyperglycaemia, and 48 mmol/mol or above may be diagnostic of diabetes when confirmed on a second test in an asymptomatic person.

NICE guidelines (NG28) provide clear thresholds for interpreting HbA1c results in adults. Understanding where your result falls helps contextualise what action, if any, may be needed:

• Below 42 mmol/mol: Considered within the normal range; diabetes is unlikely.

• 42–47 mmol/mol: Classified as non-diabetic hyperglycaemia (sometimes called prediabetes). This indicates an elevated risk of developing type 2 diabetes and warrants lifestyle intervention and regular monitoring.

• 48 mmol/mol or above: May be diagnostic of diabetes when confirmed on a second test in an asymptomatic person (unless symptoms are present, in which case a single result may suffice).

Importantly, HbA1c alone cannot determine the type of diabetes. Further clinical assessment is needed to distinguish between type 1, type 2, and other forms of diabetes.

HbA1c should not be used to diagnose diabetes in the following situations, where plasma glucose–based testing (fasting plasma glucose or OGTT) should be used instead:

• Children and young people

• Pregnant women

• People with suspected type 1 diabetes

• People whose symptoms have been present for fewer than 2 months

• People with conditions affecting red blood cell turnover (e.g., haemoglobinopathies, haemolytic anaemia, recent blood transfusion)

• People with acute pancreatic damage or pancreatic surgery

For people already diagnosed with diabetes, HbA1c targets are individualised based on factors including treatment regimen, risk of hypoglycaemia, frailty, comorbidities, and patient preference. As a general guide, NICE recommends a target of 48 mmol/mol (6.5%) for most people with type 2 diabetes managed by lifestyle or metformin alone, and 53 mmol/mol (7.0%) for those on medications that carry a risk of hypoglycaemia, such as sulphonylureas or insulin. Your clinician will agree a personalised target with you.

It is important to remember that HbA1c is one component of diabetes assessment. Clinicians will also consider blood pressure, cholesterol, kidney function (eGFR and urine albumin-to-creatinine ratio), weight, and cardiovascular risk when making management decisions. A single HbA1c result should always be interpreted in the context of the full clinical picture.

What Happens After You Receive Your HbA1c Results

Next steps depend on your result: a normal result may require routine monitoring, a prediabetic result triggers referral to the NHS Diabetes Prevention Programme, and a diagnostic result leads to a structured diabetes care plan including metformin and diabetes education.

The next steps following your HbA1c result will depend on the value returned and your existing medical history. Your GP or practice nurse will typically review the result and determine the most appropriate course of action.

If your result is in the normal range and you have no risk factors for diabetes, no immediate action may be required. Your GP may recommend a repeat test as part of routine health monitoring — for example, as part of the NHS Health Check (offered every 5 years to adults aged 40–74), or more frequently (at least every 3 years) if you are considered at higher risk, for instance due to significant weight gain, a family history of type 2 diabetes, or a new diagnosis of polycystic ovary syndrome.

If your result indicates non-diabetic hyperglycaemia (42–47 mmol/mol), you are likely to be referred to the NHS Diabetes Prevention Programme (NHS DPP) — a free, evidence-based behavioural intervention programme available across England. This programme supports patients in making sustainable lifestyle changes, including dietary modification and increased physical activity, and has been shown in UK evaluations to substantially reduce the risk of progression to type 2 diabetes. Your GP can provide further information about eligibility and local availability.

If your result is diagnostic of diabetes (≥48 mmol/mol on a confirmatory test, or a single result in a symptomatic person), your GP will arrange further assessment to determine the type of diabetes, initiate a structured diabetes care plan, and discuss management options. For most people with type 2 diabetes, metformin is recommended as first-line pharmacotherapy in line with NICE NG28 guidance, alongside lifestyle support. You will also be referred for structured diabetes education (such as the DESMOND programme), enrolled in annual diabetes review checks, and referred to the NHS Diabetic Eye Screening Programme.

If you are prescribed medicines such as insulin or sulphonylureas and experience any suspected side effects — including symptoms of hypoglycaemia — you can report these via the MHRA Yellow Card scheme (available at yellowcard.mhra.gov.uk or through the NHS App).

When to Contact Your GP About a Delayed or Abnormal Result

Contact your GP if no result has been communicated within 10 working days, or sooner if you develop symptoms such as excessive thirst, unexplained weight loss, or fatigue; seek urgent same-day care if symptoms of diabetic ketoacidosis or severe hypoglycaemia develop.

If you have had an HbA1c blood test and have not received any communication from your GP surgery within 10 working days, it is advisable to contact the practice directly. Results can occasionally be delayed, misfiled, or overlooked in busy clinical settings, and it is always appropriate to follow up proactively — particularly if the test was requested to investigate symptoms.

Contact your GP promptly if you experience any of the following symptoms while awaiting or following your result:

• Excessive thirst or frequent urination

• Unexplained weight loss

• Persistent fatigue or blurred vision

• Slow-healing wounds or recurrent infections

• Tingling or numbness in the hands or feet

These may indicate poorly controlled or undiagnosed diabetes and should not be left unaddressed while waiting for administrative processes to complete.

If your result comes back significantly elevated, or if you have symptoms of hyperglycaemia, your GP may wish to see you promptly to begin treatment and assess for complications. The urgency of review will depend on your symptoms and overall clinical picture rather than a fixed HbA1c threshold, and your GP will advise accordingly.

If you are already on diabetes medication — particularly insulin or a sulphonylurea — and your HbA1c is unexpectedly low, this may suggest a risk of hypoglycaemia and your treatment regimen may need reviewing with your clinician. Targets should always be individualised.

Seek urgent same-day medical attention (call 111 or attend A&E, or call 999 in an emergency) if you or someone else develops any of the following:

• Vomiting, severe abdominal pain, drowsiness, confusion, deep or rapid breathing, or signs of severe dehydration (which may indicate diabetic ketoacidosis or hyperosmolar hyperglycaemic state)

• Severe hypoglycaemia (very low blood sugar causing confusion, seizure, or loss of consciousness)

Do not wait for a routine appointment if these symptoms are present.

For general queries about your results, the NHS App allows many patients to view test results directly once they have been reviewed by a clinician. Your GP surgery can advise on how to access this service if you are not already registered.

Frequently Asked Questions