Enter the concentration of insulin and the concentration of C peptide into the calculator to determine the insulin C peptide ratio.

Insulin C Peptide Ratio Calculator

Enter any 2 values to calculate the missing variable

Disclaimer: For educational purposes only; not medical advice and not for diagnosis or medication changes. Unit conversions used here are approximate and can vary by laboratory/assay—use your lab’s reported units and reference ranges, and consult a qualified clinician for interpretation (especially with symptoms of hypoglycemia or concerns about diabetes/endocrine disorders).

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Insulin C Peptide Ratio Formula

The following formula is used to calculate the insulin C peptide ratio for given concentrations of insulin and C peptide.

R = I / C

Variables:

  • R is the insulin/C‑peptide ratio (Insulin in µIU/mL ÷ C‑peptide in ng/mL)
  • I is the concentration of insulin (µIU/mL, numerically equal to mU/L)
  • C is the concentration of C peptide (ng/mL)

To calculate the insulin/C‑peptide ratio, divide the concentration of insulin (µIU/mL ≈ mU/L) by the concentration of C peptide (ng/mL).

What is the Insulin C Peptide Ratio?

The insulin/C‑peptide ratio is a measure used to compare insulin and C‑peptide concentrations in the blood. Clinicians may use it as part of a broader evaluation of insulin production and secretion. Insulin and C‑peptide are secreted in equimolar amounts when proinsulin is cleaved, but their blood levels are not “equal” because insulin is cleared more rapidly (including by the liver) while C‑peptide has a longer half-life. Because interpretation depends on timing, glucose level at the time of draw, kidney function, lab method, and medication use, the ratio should be interpreted in clinical context.

How to Calculate Insulin C Peptide Ratio?

The following steps outline how to calculate the Insulin C Peptide Ratio.

  1. First, determine the concentration of insulin (I).
  2. Next, determine the concentration of C peptide (C).
  3. Finally, calculate the insulin C peptide ratio using the formula R = I / C.
  4. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Concentration of Insulin (I) = 10 mU/L (≈ µIU/mL)

Concentration of C Peptide (C) = 5 ng/mL