# A1C ↔ eAG

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/a1c_eag`
HTML: https://magentlab.com/docs/a1c-eag
Markdown: https://magentlab.com/docs/a1c-eag.md

Not a medical device. Not a diagnosis, dose, or listing recommendation.

## What it computes

Convert A1C percent to estimated average glucose, or the reverse, using Nathan/ADAG.

## When to use

When an agent must apply 28.7×A1C−46.7 instead of inventing an eAG from training data.

## When not to use

- Not a diagnosis. Provide exactly one of a1c_percent or eAG (mg/dL or mmol/L).
- Does not interpret a glucose meter log or diagnose diabetes.

## Formula

```
eAG_mg_dl = 28.7 * A1C_percent - 46.7
```

## Citation

Translating the A1C assay into estimated average glucose values
Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ
Diabetes Care. 2008;31(8):1473-1478
DOI: [10.2337/dc08-0545](https://doi.org/10.2337/dc08-0545)

## Worked example

### A1C 7.0 → eAG

Given: `a1c_percent=7.0`

1. eAG = 28.7 * 7.0 - 46.7 = 154.2 mg/dL
2. mmol/L = 154.2 / 18


## Parameters

- `a1c_percent` (number, optional): HbA1c in percent (4-15). Provide this or an eAG, not both.
- `eag_mg_dl` (number, optional): Estimated average glucose in mg/dL (50-500).
- `eag_mmol_l` (number, optional): Estimated average glucose in mmol/L. Converted as mg/dL = mmol/L * 18.

## Bulk (POST)

POST the same path with a JSON items array. Price is n times the GET unit. Invalid items return HTTP 400 before settlement.

Method: `POST /api/calc/a1c_eag`
Max items: 25
Price: unit_amount * n (unit 5000 atomic)
Status: PREVIEW

- 1 to 25 items. Each item uses the same keys as the GET query parameters.
- The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
- HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
- Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
- x402 resource URL is this path plus n and body_sha256. HTML paywall is GET only.

Example request:

```json
{
  "items": [
    {
      "a1c_percent": "7.0"
    },
    {
      "a1c_percent": "7.0"
    }
  ]
}
```

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/a1c_eag",
  "items": [
    {
      "direction": "a1c_to_eag",
      "eag_mg_dl": 154.2,
      "disclaimer": "Not a medical device. Deterministic published-formula or coded-ontology output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "a1c_percent": 7.0,
      "citation": {
        "authors": "Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ",
        "doi": "10.2337/dc08-0545",
        "id": "nathan-2008",
        "source": "Diabetes Care. 2008;31(8):1473-1478",
        "title": "Translating the A1C assay into estimated average glucose values"
      },
      "eag_mmol_l": 8.6,
      "formula": "nathan_adag",
      "formula_expression": "eAG_mg_dl = 28.7 * A1C_percent - 46.7"
    },
    {
      "direction": "a1c_to_eag",
      "eag_mg_dl": 154.2,
      "disclaimer": "Not a medical device. Deterministic published-formula or coded-ontology output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "a1c_percent": 7.0,
      "citation": {
        "authors": "Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ",
        "doi": "10.2337/dc08-0545",
        "id": "nathan-2008",
        "source": "Diabetes Care. 2008;31(8):1473-1478",
        "title": "Translating the A1C assay into estimated average glucose values"
      },
      "eag_mmol_l": 8.6,
      "formula": "nathan_adag",
      "formula_expression": "eAG_mg_dl = 28.7 * A1C_percent - 46.7"
    }
  ]
}
```

## Response fields

- `formula` (string): nathan_adag
- `formula_expression` (string): Exact expression used
- `direction` (string): a1c_to_eag or eag_to_a1c
- `a1c_percent` (number): A1C %, 1 decimal
- `eag_mg_dl` (number): eAG in mg/dL, 1 decimal
- `eag_mmol_l` (number): eAG in mmol/L (mg/dL / 18), 1 decimal
- `citation` (object): Nathan Diabetes Care 2008
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "direction": "a1c_to_eag",
  "eag_mg_dl": 154.2,
  "disclaimer": "Not a medical device. Deterministic published-formula or coded-ontology output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "a1c_percent": 7.0,
  "citation": {
    "authors": "Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ",
    "doi": "10.2337/dc08-0545",
    "id": "nathan-2008",
    "source": "Diabetes Care. 2008;31(8):1473-1478",
    "title": "Translating the A1C assay into estimated average glucose values"
  },
  "eag_mmol_l": 8.6,
  "formula": "nathan_adag",
  "formula_expression": "eAG_mg_dl = 28.7 * A1C_percent - 46.7"
}
```

## Errors

- HTTP 400 `invalid_a1c_input`: provide a1c_percent or eag_mg_dl/eag_mmol_l, not both Returned before settlement; you are not charged.
- HTTP 400 `invalid_a1c`: a1c_percent must be a number from 4 to 15 Returned before settlement; you are not charged.
- HTTP 400 `invalid_eag`: eag_mg_dl (50-500) or eag_mmol_l (2.8-27.8) is required Returned before settlement; you are not charged.
- HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
- HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
- HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged.
- HTTP 402 `payment_required`: Missing or invalid PAYMENT-SIGNATURE; decode the PAYMENT-REQUIRED header
- HTTP 409 `payment_in_progress`: The same authorization nonce is already being settled; retry shortly
- HTTP 429 `rate_limited`: Too many requests from this client
- HTTP 503 `settlement_uncertain`: Settlement is unconfirmed; retry with the same PAYMENT-SIGNATURE
- HTTP 503 `facilitator_unavailable`: Payment facilitator unavailable
- HTTP 503 `facilitator_misconfigured`: Payment facilitator is not configured
- HTTP 503 `facilitator_unauthorized`: Payment facilitator rejected credentials
- HTTP 503 `ledger_unavailable`: Payment ledger unavailable
- HTTP 503 `payment_unavailable`: Payment processing unavailable

## Related tools

- [Corrected calcium](https://magentlab.com/docs/corrected-calcium) — Compute Payne albumin-corrected calcium from total calcium and albumin.

## Also searched as

- Nathan ADAG
- A1C to eAG 28.7
- estimated average glucose
- HbA1c eAG

## Payment

Required query parameters must be present and valid. Invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s.

## Guarantees

- Invalid query parameters return HTTP 400 before settlement. You are not charged.
- Settlement finishes before the tool executes. Uncertain settlement fails closed (HTTP 503).
- Execution is timeout-bounded and concurrency-capped.
- Calculator inputs are not persisted. Request logs store path without query.