In this article

What is C-peptide?

C-peptide is a substance your body makes alongside insulin, the hormone that helps control blood sugar. When your body produces insulin, it also releases C-peptide in equal amounts. By measuring C-peptide levels, doctors can see how much insulin your body is making on its own. This is especially useful for people with diabetes because C-peptide levels are not affected by insulin injections, so it gives a clear picture of natural insulin production.

Why is C-peptide important?

C-peptide levels help doctors understand how well your pancreas is working, especially in terms of making insulin. For people with type 1 diabetes, low or no C-peptide usually means the body isnโ€™t making much, if any, insulin. In type 2 diabetes, higher C-peptide levels can show that the body is making insulin, but it might not be using it effectively (a condition called insulin resistance). Measuring C-peptide can help identify the type of diabetes, check remaining insulin-producing cells, and guide insulin treatment decisions.

How can I better understand my C-peptide levels?

According to the NIH, the normal reference interval for fasting patients are as follows [1]:

  • Out of range: 0-1.1 ng/mL
  • In range: 1.1-4.4 ng/mL
  • Out of range: 4.4+ ng/mL

Low C-peptide:ย Indicates low insulin production, often associated with type 1 diabetes, late-stage type 2 diabetes, or pancreatic disorders.
Normal C-peptide: Typically found in healthy individuals, indicating normal insulin production.
High C-peptide: May indicate insulin resistance, often seen in early type 2 diabetes, polycystic ovary syndrome (PCOS), or insulinoma (a rare pancreatic tumor).

How can I maintain optimal C-peptide levels?

If you need to maintain or adjust your C-peptide levels, consider the following strategies [2]:

Dietary Changes: Avoid highly processed, high-carbohydrate foods and saturated fats and opt for low glycemic index foods (beans and legumes, non-starchy veggies, berries, etc.) to lower insulin levels.

Lifestyle Changes: Try exercising and losing weight by leading a healthy lifestyle to regulate insulin levels.

Medical Care: Consult your healthcare provider about medications that can impact insulin production or resistance.

Where Can I Learn More?

Medline Plus โ€“ What is a C-peptide test?

UCSF Health โ€“ Insulin C-peptide test

DISCLAIMER: IF YOU ARE CONCERNED WITH ANY OF YOUR RESULTS, PLEASE CONSULT WITH YOUR PHYSICIAN.

References[+]