A1C of 11.5% is an average glucose of 283 mg/dL

Estimated average glucose at A1C 11.5%

283 mg/dL

In mmol/L: 15.7 mmol/L
A1C entered: 11.5%
ADA range: the range the ADA uses to diagnose diabetes

At 11.5%, the estimated average glucose works out to 283 mg/dL (15.7 mmol/L). If your report uses IFCC units instead of a percentage, the equivalent is around 102 mmol/mol.

The ADA uses 6.5% and above as one of its diagnostic criteria for diabetes, and normally asks for a confirmatory test before diagnosing. What that means for you is a conversation for your clinician, not for a calculator.

One tenth higher, at 11.6%, the estimate reaches about 286 mg/dL — a difference of roughly 3 mg/dL. Set against the 0.5 percentage points a certified assay may vary by, that is a very small step indeed.

Writing the value and its date somewhere you will find it again is worth more than reading another page about it, because the comparison is the part that carries information.

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.

Convert a different A1C value

A1C to estimated average glucose, 11.0% to 12.0%
A1C	eAG (mg/dL)	eAG (mmol/L)
11.0%	269 mg/dL	14.9 mmol/L
11.1%	272 mg/dL	15.1 mmol/L
11.2%	275 mg/dL	15.3 mmol/L
11.3%	278 mg/dL	15.4 mmol/L
11.4%	280 mg/dL	15.5 mmol/L
11.5%	283 mg/dL	15.7 mmol/L
11.6%	286 mg/dL	15.9 mmol/L
11.7%	289 mg/dL	16 mmol/L
11.8%	292 mg/dL	16.2 mmol/L
11.9%	295 mg/dL	16.4 mmol/L
12.0%	298 mg/dL	16.5 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 11.5% equals what blood sugar?

283 mg/dL is the estimate, which is 15.7 mmol/L. It follows directly from the ADAG regression applied to 11.5%, and represents a population average rather than your personal figure.

What does the ADA say about 11.5%?

The ADA describes 11.5% 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.

Is 11.5% the same in mmol/mol?

Some countries report A1C in IFCC units rather than NGSP percent. 11.5% is approximately 102 mmol/mol, so a report from the UK, Australia or much of Europe may show that number instead.

What time period does an A1C of 11.5% 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.

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