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Guide

Normal A1C range, prediabetes and diabetes levels

What counts as a normal HbA1c, what the prediabetes range means and why the cut-offs for diagnosis are not the same as treatment targets, in % and mmol/mol.

The three A1C ranges

The American Diabetes Association (ADA) Standards of Care use these A1C ranges for diagnosis in adults:

  • Below 5.7% (below 39 mmol/mol): normal
  • 5.7% to 6.4% (39–47 mmol/mol): prediabetes, a higher risk of developing type 2 diabetes
  • 6.5% or higher (48 mmol/mol or higher): diabetes, usually confirmed by repeating the test or with a glucose test

In the UK, NICE uses 42–47 mmol/mol (6.0–6.4%) for “non-diabetic hyperglycaemia”, the British term for prediabetes. The cut-off for diabetes is the same.

A1C levels at a glance

IFCC mmol/mol = (A1C − 2.15) × 10.929, rounded. Ranges per the ADA.
A1C (%)A1C (mmol/mol)ADA range
4.829Normal
5.031Normal
5.436Normal
5.638Normal
5.739Prediabetes
6.042Prediabetes
6.446Prediabetes
6.548Diabetes
7.053Diabetes
7.558Diabetes
8.064Diabetes

Most people without diabetes have an A1C between about 4.8% and 5.6%.

Glucose tests used alongside A1C

Diabetes can also be diagnosed with fasting plasma glucose or a 2-hour oral glucose tolerance test (OGTT). The ADA cut-offs side by side:

ADA diagnostic cut-offs for adults. mmol/L = mg/dL ÷ 18.016, rounded.
RangeA1CFasting glucose2 hours after OGTT
Normalbelow 5.7% (39 mmol/mol)below 100 mg/dL (5.6 mmol/L)below 140 mg/dL (7.8 mmol/L)
Prediabetes5.7–6.4% (39–47 mmol/mol)100–125 mg/dL (5.6–6.9 mmol/L)140–199 mg/dL (7.8–11.0 mmol/L)
Diabetes6.5% or higher (48 mmol/mol)126 mg/dL or higher (7.0 mmol/L)200 mg/dL or higher (11.1 mmol/L)

The tests do not always agree with each other. Doctors look at the whole picture, and a single result is not a diagnosis.

Prediabetes is common and often reversible

More than a third of US adults have prediabetes, and most of them don’t know it. It is not a diagnosis of diabetes. In the Diabetes Prevention Program, modest weight loss (about 5–7% of body weight) and about 150 minutes of brisk activity a week cut the risk of progressing to type 2 diabetes by more than half.

If your result is in this range, a calm next step is to ask your doctor when to test again and whether a structured lifestyle programme is available to you.

Diagnostic ranges vs. treatment targets

The ranges above are for finding out whether someone has diabetes. Once diabetes is diagnosed, the question becomes which target is safe and realistic for you. For many non-pregnant adults the ADA suggests an A1C below 7% (53 mmol/mol). A tighter goal may suit younger people with a low risk of hypoglycemia; a looser goal, often below 8% (64 mmol/mol), is common for older adults or people with other health conditions.

Targets in pregnancy are lower and are set by the obstetric and diabetes team.

Does A1C change with age?

A1C tends to rise slightly with age even in people without diabetes, by roughly 0.1 percentage point per decade. The diagnostic cut-offs are still the same for all adults. Treatment targets, on the other hand, are often relaxed for older adults to avoid low blood sugar.

Common questions

Is an A1C of 5.7% bad?

5.7% is the lower edge of the prediabetes range. It signals a higher risk of type 2 diabetes in the future and is a good moment to look at activity, diet and weight with your doctor. Many people with this result never develop diabetes.

What A1C confirms diabetes?

6.5% (48 mmol/mol) or higher, normally confirmed by a second test, unless there are clear symptoms together with a very high glucose reading.

This page is for information only and is not medical advice.

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