HbA1c test: what it is, the normal range and what results mean

An HbA1c test measures how much of the haemoglobin in your red blood cells has glucose attached. Red blood cells live about 120 days, so the result reflects your average blood sugar over roughly the past two to three months, not the morning of the test. It is used to screen for prediabetes and type 2 diabetes and to follow blood sugar over time, and it needs no fasting.

What HbA1c measures

Haemoglobin is the protein in red blood cells that carries oxygen. Glucose in the blood attaches to it and stays for the life of the cell, so the more glucose there has been, the larger the share of haemoglobin that carries it. HbA1c is that share. It is a weighted average: recent weeks count for more than older ones, so a real change in blood sugar can show before the full 120 days have passed.

Most reports give a percentage, the NGSP unit used by the American Diabetes Association (ADA), and many also give mmol/mol, the IFCC unit. They are linked by mmol/mol = (10.93 × %) - 23.50, so 6.5% is 48 mmol/mol.

HbA1c normal range

The ADA uses these bands for adults who are not pregnant.

Risk does not switch on at a line: the ADA describes it as continuous, starting below 5.7% and rising faster near the top of the prediabetes range. One result at or above 6.5% is not a diagnosis by itself; without clear symptoms, the ADA asks for two abnormal results, from the same test repeated or from two different tests. Other bodies draw the lines elsewhere: NICE in the UK treats 42 to 47 mmol/mol (6.0% to 6.4%) as high risk.

Ranges also vary with the laboratory and method, and MedlinePlus notes that what is normal depends on a person's health and age, so read your result against the range on your own report. For many non-pregnant adults who have diabetes, the ADA suggests a goal below 7% (53 mmol/mol), set individually with a doctor.

What a high result usually points to

A result in the prediabetes range usually means blood sugar has been running above the usual level for some months. A result of 6.5% or above, once confirmed, meets the ADA's criterion for diabetes. Neither is read alone.

A doctor will typically repeat the HbA1c or add a fasting glucose or oral glucose tolerance test, and read the results beside risk factors such as weight, blood pressure and family history. When HbA1c and glucose disagree, the ADA recommends looking for the reason: iron deficiency anaemia is linked with a higher HbA1c, and so is anything that makes red cells live longer than usual.

What a low result usually points to

A low HbA1c can reflect low average glucose, or red cells that are younger than usual. Recovery from blood loss, haemolytic anaemia, a recent transfusion and treatment that stimulates red cell production all lower HbA1c whatever method the laboratory uses. Some inherited haemoglobin variants and glucose-6-phosphate dehydrogenase (G6PD) deficiency can also move the result, depending on the method.

A doctor will usually look at the full blood count and for signs of bleeding or red cell breakdown. Where HbA1c cannot be relied on, the ADA lists fructosamine or continuous glucose monitoring instead.

What moves HbA1c

• Red cell lifespan. Anaemia, iron status, removal of the spleen, blood loss, transfusion, haemolysis, G6PD deficiency and erythropoietin treatment are all on the ADA's list.
• Haemoglobin variants. HbS, HbC, HbE and HbD traits and raised fetal haemoglobin interfere with some methods and not others; the NGSP lists them by method.
• Kidneys and liver. Kidney failure, dialysis and cirrhosis can all affect the result.
• Pregnancy. HbA1c is less reliable in pregnancy and tends to rise late in pregnancy as iron runs low.
• Medicines and infections. MedlinePlus lists opioids and some HIV medicines, and HIV itself is on the ADA's list.
• Laboratory factors. Very high triglycerides or bilirubin can interfere with some methods.

The day itself matters little: the ADA notes that a recent meal, stress, illness or exercise do not affect HbA1c, and that it varies little from day to day in the same person.

Preparing for the test

No fasting is needed and the time of day does not matter, unless the same sample is also used for fasting glucose or fasting insulin.

Tell the person taking the sample if you are pregnant, have had blood loss or a transfusion in recent months, have anaemia, a kidney condition or a known haemoglobin trait such as thalassaemia, or take regular medicines. The doctor can then judge whether HbA1c suits you or needs a second measure beside it.

How Clare's panel handles it

In Clare's panel, HbA1c is measured by the lab, and Clare calculates Estimated Average Glucose (eAG) from it with the ADAG study's equation, eAG (mmol/L) = 1.59 × HbA1c (%) - 2.59. When Clare opens, HbA1c will sit in one account with fasting glucose, fasting insulin and past results, so each new value can be read against the last.

Why it matters in the UAE

The International Diabetes Federation estimates that 20.7% of UAE adults aged 20 to 79 had diabetes in 2024 (age-standardised), about 1.27 million people, around 64% of them undiagnosed. The ADA explains the gap: type 2 diabetes develops gradually, often without clear early symptoms, which is why guidelines screen for it with blood tests such as HbA1c.

Inherited haemoglobin conditions are also common in the UAE. A 2017 review put the beta-thalassaemia carrier rate at 8.5%, and premarital screening has been mandatory for couples since 2012. Because thalassaemia and haemoglobin variants can affect HbA1c with some methods, it is worth saying so when the sample is taken if you know you carry one.

Price

When we read public prices on 11 October 2026, an HbA1c test on its own cost from 45 to 149 at 3 UAE providers. VAT was rarely stated, one figure came from a price table the provider described as indicative, and home collection can add a fee.

Related tests

HbA1c is usually read with Fasting Glucose, the same picture on one morning. Ferritin and Hemoglobin help explain an HbA1c that does not fit the glucose results. The article HbA1c, glucose and insulin: reading them together walks through how they fit.

HbA1c over time

One HbA1c covers about three months; repeated results show direction. The ADA suggests repeating screening at least every three years when results are normal, sooner if risk changes, yearly in the prediabetes range, and within 3 to 6 months for a result close to the diabetes threshold. People with diabetes are usually tested at least twice a year, and about every 3 months when treatment changes or goals are not met. Because HbA1c varies little from day to day, a steady change across results on the same method means more than the same change in one glucose reading.

Clare is opening with a waitlist at clare.health.