A1C of 8% is an average glucose of 183 mg/dL

Estimated average glucose at A1C 8%

183 mg/dL

In mmol/L: 10.2 mmol/L
A1C entered: 8.0%
ADA range: the range the ADA uses to diagnose diabetes

An A1C of 8.0% corresponds to an estimated average glucose of 183 mg/dL, or 10.2 mmol/L, across roughly the previous two to three months. In IFCC units that A1C is about 64 mmol/mol.

The ADA diagnostic threshold is 6.5%, so this figure sits inside that range. The estimated average glucose here is a translation of the number, not an assessment of the person it belongs to.

A1C 8.0% converts to an estimated average glucose of 183 mg/dL and comes up often in discussions of glycemic management. Like every value here, the conversion is population-level arithmetic: individual mean glucose at a given A1C varies meaningfully between people.

For comparison, 8.1% comes out at approximately 186 mg/dL, about 3 mg/dL higher. Differences of a tenth sit under the roughly 0.5-point measurement tolerance, so neighbouring values are often indistinguishable in practice.

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.

Two numbers can be identical and describe quite different weeks. That is not a flaw in the measurement so much as a limit of what any average can say.

A1C looks back over roughly the previous two to three months, because it tracks glycation in red blood cells and those cells circulate for about 120 days before being replaced.

Convert a different A1C value

A1C to estimated average glucose, 7.5% to 8.5%
A1C	eAG (mg/dL)	eAG (mmol/L)
7.5%	169 mg/dL	9.4 mmol/L
7.6%	171 mg/dL	9.5 mmol/L
7.7%	174 mg/dL	9.7 mmol/L
7.8%	177 mg/dL	9.8 mmol/L
7.9%	180 mg/dL	10 mmol/L
8.0%	183 mg/dL	10.2 mmol/L
8.1%	186 mg/dL	10.3 mmol/L
8.2%	189 mg/dL	10.5 mmol/L
8.3%	192 mg/dL	10.7 mmol/L
8.4%	194 mg/dL	10.8 mmol/L
8.5%	197 mg/dL	10.9 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

An A1C of 8.0% equals what blood sugar?

183 mg/dL is the estimate, which is 10.2 mmol/L. It follows directly from the ADAG regression applied to 8.0%, and represents a population average rather than your personal figure.

Which ADA category does an A1C of 8.0% belong to?

The ADA describes 8.0% as the range the ADA uses to diagnose diabetes. 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 8.0% 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 8.0% the same in mmol/mol?

Some countries report A1C in IFCC units rather than NGSP percent. 8.0% is approximately 64 mmol/mol, so a report from the UK, Australia or much of Europe may show that number instead.

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