A1C of 14% is an average glucose of 355 mg/dL

Estimated average glucose at A1C 14%

355 mg/dL

In mmol/L: 19.7 mmol/L
A1C entered: 14.0%
ADA range: the range the ADA uses to diagnose diabetes

At 14.0%, the estimated average glucose works out to 355 mg/dL (19.7 mmol/L). If your report uses IFCC units instead of a percentage, the equivalent is around 130 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.

For comparison, 14.1% comes out at approximately 358 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.

Moving country, or moving between health systems, can change the units on your reports without anything changing in your blood. Worth checking before comparing an old result to a new one.

The conversion comes from a population regression. In the ADAG study, individuals sharing an A1C had mean glucose values spread meaningfully around the fitted line, so your own average may sit above or below this estimate.

What this number cannot show is glucose variability. Continuous monitoring data reveals a pattern through the day that no single averaged figure can express.

Because the measurement covers a rolling window of months, retesting much sooner than three months largely re-measures the same period and adds little information.

Convert a different A1C value

A1C to estimated average glucose, 13.5% to 14.0%
A1C	eAG (mg/dL)	eAG (mmol/L)
13.5%	341 mg/dL	18.9 mmol/L
13.6%	344 mg/dL	19.1 mmol/L
13.7%	346 mg/dL	19.2 mmol/L
13.8%	349 mg/dL	19.4 mmol/L
13.9%	352 mg/dL	19.5 mmol/L
14.0%	355 mg/dL	19.7 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

14.0% A1C is what in average glucose?

Around 355 mg/dL — 19.7 mmol/L if your readings use that scale. The conversion for 14.0% comes from the ADAG study regression published in 2008.

How does the ADA describe an A1C of 14.0%?

The ADA describes 14.0% 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.

Can something other than glucose produce an A1C of 14.0%?

Yes. Anaemia, recent blood loss, transfusion, pregnancy, chronic kidney disease and some haemoglobin variants all shift A1C independently of glucose, in either direction.

Does an A1C of 14.0% tell me about my glucose swings?

No. It is an average, and averages hide shape. Two people with this same A1C can have very different daily ranges; continuous monitoring is what shows that pattern.

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