A1C of 5.2% is an average glucose of 103 mg/dL
Estimated average glucose at A1C 5.2%
103 mg/dL
- In mmol/L
- 5.7 mmol/L
- A1C entered
- 5.2%
- ADA range
- below the range the ADA defines as prediabetes
An A1C of 5.2% corresponds to an estimated average glucose of 103 mg/dL, or 5.7 mmol/L, across roughly the previous two to three months. In IFCC units that A1C is about 33 mmol/mol.
The ADA defines prediabetes as beginning at 5.7%, so this value is under that line. What it cannot tell you is how much your glucose swings through the day — two people with an identical A1C can have very different daily ranges.
A1C 5.2% is the kind of result people read once and move on from, which is reasonable. If you are tracking it anyway, the useful comparison is not against the threshold but against your own previous value, and even then only a change of more than about half a point is larger than what the assay itself can wobble by.
Step up one tenth and the estimate moves by around 2 mg/dL: 5.3% gives about 105 mg/dL. Since a certified assay may itself vary by roughly 0.5 percentage points, a single tenth of movement between two tests is not really movement.
An average hides shape. Two people with the same A1C can have very different days — one steady, one swinging widely — and A1C does not distinguish between them at all.
The look-back is weighted rather than even: the most recent weeks contribute more to the figure than the earliest ones, which is why an A1C moves before a full three months have passed.
A point-of-care fingerstick A1C and a venous laboratory draw can read differently on the same day. If two of your results disagree, the sample type is worth checking before anything else.
A sensible thing to ask at the next appointment is what this figure is expected to do, and when it will next be measured — which turns a number into something you can actually follow.
| A1C | eAG (mg/dL) | eAG (mmol/L) |
|---|---|---|
| 4.7% | 88 mg/dL | 4.9 mmol/L |
| 4.8% | 91 mg/dL | 5.1 mmol/L |
| 4.9% | 94 mg/dL | 5.2 mmol/L |
| 5.0% | 97 mg/dL | 5.4 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 |
- Estimated average glucose (ADAG / Nathan) — eAG (mg/dL) = 28.7 x A1C - 46.7. Verified 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
What does 5.2% convert to in mg/dL?
How does the ADA describe an A1C of 5.2%?
Can something other than glucose produce an A1C of 5.2%?
Does an A1C of 5.2% tell me about my glucose swings?
Get a quarterly nudge to re-check your numbers
Four emails a year: a reminder to re-take your numbers, and what changed in the guidance behind these tools. No spam, unsubscribe any time.
Double opt-in: you will get one confirmation email and nothing else until you click it.