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C-Peptide Unit Converter
C-Peptide (Connecting Peptide) is a short 31-amino-acid polypeptide that connects insulin’s A-chain to its B-chain in the proinsulin molecule. Within the beta cells of the pancreas, proinsulin is cleaved to release insulin and C-peptide in equimolar amounts (1:1 ratio).[Image of proinsulin cleavage into insulin and c-peptide]
Because C-peptide is secreted in a 1:1 ratio with insulin but has a longer half-life and is not extracted by the liver as heavily as insulin, it is the most reliable marker of endogenous insulin production. It is crucial for distinguishing between Type 1 Diabetes (low/absent C-peptide) and Type 2 Diabetes (normal/high C-peptide). It is also essential in the investigation of hypoglycemia to differentiate insulinoma (high C-peptide) from factitious hypoglycemia caused by exogenous insulin administration (low C-peptide).
SI Units
RecommendedNanomoles per liter (Standard International).
Conventional Units
Clinical Context
Fasting C-Peptide levels in healthy individuals typically range from 0.8 – 3.8 ng/mL (0.26 – 1.27 nmol/L), though ranges vary by laboratory.
In the workup of hypoglycemia, a C-peptide level > 0.6 ng/mL (0.2 nmol/L) when glucose is low (< 55 mg/dL) suggests endogenous hyperinsulinism (e.g., insulinoma or sulfonylurea use). Conversely, suppressed C-peptide implies exogenous insulin administration. C-peptide is primarily cleared by the kidneys, so levels may be falsely elevated in renal failure.
Clinical References
How to Use This Calculator
Follow these steps to get accurate clinical conversions instantly.
Enter Values
Input your laboratory results into the corresponding unit field (e.g., ng/mL). You can use either dot or comma decimals.
Automatic Conversion
The calculator works in real-time. As you type in one field, all other units (like nmol/L) are instantly updated.
Verify Units
Check the SI Units section. nmol/L is the standard unit for peptide hormones.
Reset
Use the Clear button to reset all fields before starting a new calculation.
Frequently Asked Questions & Tips
Yes. 1 ng/mL is exactly equal to 1 µg/L.
1 nmol/L ≈ 3.02 ng/mL. This is derived from the molecular weight of C-peptide (3020.3 g/mol).