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Magent CPR Index (C-Peptide-to-Glucose Ratio) Calculator
x402
Magent CPR Index (C-Peptide-to-Glucose Ratio) Calculator is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).
Computes the Saisho 2011 C-Peptide Reactivity (CPR) Index from serum C-peptide and plasma glucose, and flags whether the result falls below the 2.02 cutoff predictive of later insulin therapy need.
Price / call$0.005
Success—
StatusUnknown
How this service works
Saisho 2011 CPR index: serum C-peptide (ng/mL) / plasma glucose (mg/dL) * 100, two decimals. timing fasting or postprandial (same formula; required label). below_best_cutoff true iff cpri < 2.02 (ROC for later insulin therapy; 80.8% sensitivity, 63.3% specificity). Glucose mg/dL only. Not HOMA-IR, not a diabetes diagnosis, not C-peptide alone, and not an insulin order.
Output
Returns the CPR index as a decimal value rounded to two places (C-peptide ng/mL / glucose mg/dL * 100), the sample timing label, and a boolean below_best_cutoff indicating whether the index is below 2.02 — the ROC-derived threshold associated with 80.8% sensitivity and 63.3% specificity for predicting later insulin therapy requirement.
Example use cases
Insulin therapy need screening
“My patient has a fasting serum C-peptide of 0.9 ng/mL and a plasma glucose of 180 mg/dL — can you compute their CPR index and let me know whether they fall below the threshold that suggests they'll likely need insulin later?”
Postprandial beta cell function check
“After a meal, this patient's C-peptide came back at 3.4 ng/mL and their glucose was 260 mg/dL — calculate the postprandial CPR index and flag whether it's below 2.02.”
Type 1 vs Type 2 differentiation support
“I'm trying to assess residual beta cell function for a newly diagnosed diabetic: C-peptide is 1.2 ng/mL fasting, glucose is 145 mg/dL — run the Saisho 2011 CPR index calculation and tell me the result and the cutoff flag.”
Technical details
Endpoint
GEThttps://api.magentlab.com/api/calc/cpriWhen to prefer
Use this endpoint when you need the specific Saisho 2011 CPR index arithmetic with an automated below-2.02 cutoff flag, particularly in clinical decision support workflows evaluating future insulin therapy need. Prefer it over manual calculation to avoid arithmetic errors and to get the standardized cutoff flag with its documented sensitivity/specificity. Do not use for HOMA-IR, standalone C-peptide interpretation, diabetes diagnosis, or insulin dosing orders.
Side effects
- Missing required query parameters (timing, c_peptide_ng_ml, glucose_mg_dl) returns a 400 error
- Glucose value outside 50–1000 mg/dL range rejected as invalid input
- C-peptide value outside 0–40 ng/mL range rejected
- Glucose provided in mmol/L instead of mg/dL will produce incorrect results (no unit conversion performed)
- Payment not included or insufficient USDC results in 402 Payment Required
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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