A1C of 5.6% is an average glucose of 114 mg/dL

Estimated average glucose at A1C 5.6%

114 mg/dL

In mmol/L: 6.3 mmol/L
A1C entered: 5.6%
ADA range: below the range the ADA defines as prediabetes

The estimated average glucose behind an A1C of 5.6% is 114 mg/dL, or 6.3 mmol/L. That A1C would appear as approximately 38 mmol/mol on a report using IFCC units.

This sits under the ADA prediabetes threshold. A single value summarises roughly the last three months of glucose exposure; what a clinician actually reads is the trend across several tests, which one result cannot show.

A1C 5.6% is one tenth below the ADA prediabetes range, and that proximity is exactly why people look it up. Because NGSP permits roughly half a percentage point of assay variation, a 5.6% and a 5.8% may be the same underlying glycemia measured twice.

To put the scale in context: 5.7% estimates out at around 117 mg/dL, some 3 mg/dL above this figure. Because assay tolerance spans roughly 0.5 percentage points, a shift of one tenth tells you very little on its own.

Laboratory methods differ from one another, so comparing a result from one lab against a result from another introduces a spread that has nothing to do with your glucose. Same-lab comparisons are the cleanest kind.

Bringing the printed report to an appointment beats bringing a screenshot of a calculator, because your clinician can read it against everything else in your chart.

Comparing an older report against a newer one sometimes means comparing units as well as values — a percentage against mmol/mol, or mg/dL against mmol/L. Convert before concluding anything.

Ancestry-linked haemoglobin variants can interfere with certain assay methods specifically, which is a reason a result that looks inconsistent with everything else is worth raising rather than accepting.

Convert a different A1C value

A1C to estimated average glucose, 5.1% to 6.1%
A1C	eAG (mg/dL)	eAG (mmol/L)
5.1%	100 mg/dL	5.5 mmol/L
5.2%	103 mg/dL	5.7 mmol/L
5.3%	105 mg/dL	5.8 mmol/L
5.4%	108 mg/dL	6 mmol/L
5.5%	111 mg/dL	6.2 mmol/L
5.6%	114 mg/dL	6.3 mmol/L
5.7%	117 mg/dL	6.5 mmol/L
5.8%	120 mg/dL	6.7 mmol/L
5.9%	123 mg/dL	6.8 mmol/L
6.0%	126 mg/dL	7 mmol/L
6.1%	128 mg/dL	7.1 mmol/L

Computed with eAG (mg/dL) = 28.7 x A1C - 46.7 (Nathan 2008). mmol/L is derived from mg/dL using the glucose factor 18.0182.

Estimated average glucose (ADAG / Nathan) — eAG (mg/dL) = 28.7 x A1C - 46.7. Verified 2026-07-30 against Nathan et al., Diabetes Care 2008 (ADAG study) (A population regression: in the ADAG study, individuals at the same A1C had meaningfully different mean glucose. The A1C assay itself carries about +/- 0.5 percentage points under NGSP certification.)

Official sources

Nathan DM et al., Translating the A1C Assay Into Estimated Average Glucose Values, Diabetes Care 2008 — The ADAG study that produced the eAG equation used on this page.
American Diabetes Association — Standards of Care in Diabetes — Where the A1C ranges quoted here are defined.
NGSP — A1C assay standardisation and certification criteria — Why two lab results half a point apart can mean nothing changed.

Frequently asked questions

5.6% A1C is what in average glucose?

Around 114 mg/dL — 6.3 mmol/L if your readings use that scale. The conversion for 5.6% comes from the ADAG study regression published in 2008.

Which ADA category does an A1C of 5.6% belong to?

The ADA describes 5.6% as below the range the ADA defines as prediabetes. That is a definition of a numeric range rather than a diagnosis: the ADA asks clinicians to confirm results with a repeat test and to read them alongside your history.

What time period does an A1C of 5.6% describe?

Roughly the previous two to three months of glucose exposure, weighted towards the most recent weeks, because A1C tracks glycation across the lifespan of red blood cells.

Is 5.6% the same in mmol/mol?

Some countries report A1C in IFCC units rather than NGSP percent. 5.6% is approximately 38 mmol/mol, so a report from the UK, Australia or much of Europe may show that number instead.

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