C-peptide in Serum

C-peptide is co-secreted with insulin in equimolar amounts by pancreatic beta cells, so it reflects endogenous insulin production. Unaffected by injected insulin, unlike insulin itself.
Also known as:
S-C-peptide
.

C-peptide ranges

Interpret your result
"Normal" lab range for C-peptide is between 1.1 and 4.4 ng/mL:
1.1
4.4
According to OptimalDX, C-peptide should be between 1.1 and 2.1 ng/mL:
1.1
2.1
Optimal range
Optimal range for C-peptide appears to be between 1 and 2.3 ng/mL:
0
1
2.3
4.4
9
Why this optimal range?
Preliminary range is based on functional health organizations including but not limited to those listed above.

What a low value may mean:

Common reasons for low C-peptide:

  • Low C-peptide reflects reduced endogenous insulin production — classically type 1 diabetes and LADA (autoimmune beta-cell destruction), and late-stage type 2 diabetes with beta-cell exhaustion.

    Other causes: exogenous insulin therapy suppressing pancreatic secretion, pancreatectomy or pancreatic damage, and prolonged fasting or low food intake.

    ,,

What a high value may mean:

Common reasons for high C-peptide:

  • High C-peptide reflects excess endogenous insulin production — most often the compensatory hyperinsulinemia of insulin resistance seen in obesity, metabolic syndrome, and early type 2 diabetes.

    Other causes: insulinoma (insulin-secreting tumor), Cushing's syndrome, insulin-stimulating drugs such as sulfonylureas, and reduced renal clearance in kidney insufficiency.

    ,,

Get the Full Picture of Your Glucose Metabolism

Provides a comprehensive metabolic assessment of blood glucose control using a static multi-biomarker approach.

View Full Analysis

100% free and private. Enter only the values you have.

About the site author

My personal mission is to extend human lifespan by collectively adding 1 million years to people's lives.

That’s why I made this site 100% free, no sign-up, no email. Just instant results.

Zsolt Szabo
Zsolt Szabo
Precision Health Consultant for Longevity Clinics

Please send me relevant research and feedback.

Any feedback is welcome at .
I am particularly interested in research on biomarkers associated with all-cause mortality and on defining optimal reference ranges.