C-PEPTIDE, SERUM

C-Peptide, Serum

What it is

The C-Peptide, Serum test measures the level of C-peptide in the blood. C-peptide is a byproduct created when the pancreas produces insulin. Because it is released into the bloodstream in equal amounts to insulin, C-peptide levels serve as an indirect marker of how much insulin the body is making. Unlike insulin, C-peptide remains in the blood longer, making it a more reliable indicator of pancreatic function.

Uses

This test is mainly used to evaluate insulin production, differentiate between type 1 and type 2 diabetes, and monitor patients with diabetes. It is also helpful in diagnosing insulinoma (a rare insulin-producing tumor), assessing hypoglycemia causes, and monitoring how well treatments such as insulin injections or pancreas transplants are working.

Symptoms That May Lead to the Test

Your doctor may order this test if you have unexplained low blood sugar (hypoglycemia), symptoms of diabetes, or suspected pancreatic disorders. It may also be used when distinguishing between diabetes types or when evaluating the effectiveness of therapy in individuals with insulin resistance.

Abnormal Results

Low C-Peptide: May indicate type 1 diabetes, advanced type 2 diabetes with low pancreatic reserve, or damage to pancreatic beta cells. It can also occur after pancreatic surgery.

High C-Peptide: May suggest type 2 diabetes, insulin resistance, obesity, or an insulinoma. It can also be seen in patients with kidney disease due to reduced clearance of C-peptide.

Risks

The test involves a routine blood draw. Risks are minimal and may include slight pain, bruising, or dizziness at the needle site, which usually resolve quickly.