C-Peptide

The pancreas produces insulin in the form of a precursor molecule called proinsulin. Proinsulin consists of three parts: the A-chain, the B-chain, and the C-peptide. During the maturation process, proinsulin is cleaved by proteolytic enzymes, resulting in the formation of one molecule of insulin and one molecule of C-peptide . Both insulin and C-peptide are stored in secretory granules of the pancreatic beta cells and are released into the bloodstream in equimolar amounts when blood sugar levels rise .

C-peptide was initially considered an inactive byproduct of insulin production. However, research has shown that it has both anti-inflammatory and pro-inflammatory effects in the body, depending on its levels . C-peptide levels are a reliable measure of insulin production and beta-cell function because it is broken down at a steady rate by the kidneys, unlike insulin, which is broken down at a variable rate by the liver .

A C-peptide test is a valuable diagnostic tool used to:

• Measure the amount of insulin produced by the body.
• Differentiate between type 1 and type 2 diabetes.
• Monitor diabetes management and adjust insulin dosage.
• Investigate causes of hypoglycemia (low blood sugar levels).
• Diagnose and monitor pancreatic tumors or post-pancreas transplantation .

Moderate levels of C-peptide can lower inflammation, while higher levels are associated with insulin resistance, metabolic syndrome, heart disease, and cancer . In healthy, non-diabetic individuals, C-peptide levels increase with weight and age. However, in diabetics, C-peptide levels decline over time .