C-peptide in serum

The reference values (norm) of the concentration of C-peptide in the serum in adults are 0.78-1.89 ng / ml.

C-peptide - a fragment of the molecule of proinsulin, as a result of the cleavage of which forms insulin. Insulin and C-peptide are secreted into the blood in equimolar amounts. The half-life of the C-peptide in the blood is higher than that of insulin, so the C-peptide / insulin ratio is 5: 1. Determination of the concentration of C-peptide in the blood makes it possible to characterize the residual synthetic function of beta cells in patients with diabetes mellitus. C-peptide, in contrast to insulin, does not cross-react with insulin antibodies, which allows its level to determine the content of endogenous insulin in patients with diabetes mellitus. Given that insulin medications do not contain the C-peptide, its determination in the blood serum makes it possible to evaluate the function of beta cells of the pancreas in diabetic patients receiving insulin. In a patient with diabetes mellitus, the value of basal C-peptide level and especially its concentration after loading with glucose (during PTTG) allows to determine the presence of resistance or sensitivity to insulin, to determine the phases of remission and thereby adjust the therapeutic measures. When exacerbation of diabetes, especially type 1, the concentration of C-peptide in the blood decreases, which indicates the insufficiency of endogenous insulin.

In clinical practice, the determination of C-peptide in the blood is used to establish the cause of the resulting hypoglycemia. In patients with insulinoma, there is a significant increase in the concentration of C-peptide in the blood. To confirm the diagnosis, a test is performed to suppress the formation of the C-peptide. In the morning, the patient was taken blood to determine the C-peptide. Then, for 1 hour, insulin is injected intravenously from 0.1 U / kg and blood is taken again. If the C-peptide level decreases less than 50% after insulin administration, it can be assumed with confidence that an insulin secretant tumor exists.

Monitoring the content of C-peptide is especially important in patients after operative treatment of insulinoma, detection of an elevated C-peptide in the blood indicates a metastasis or a relapse of the tumor.

Change in C-peptide concentrations in serum for various diseases and conditions

C-peptide increased

• Insulinoma
• Chronic Renal Failure

C-peptide reduced

• Introduction of exogenous insulin
• Diabetes mellitus type 1
• Diabetes mellitus type 2

[1], [2], [3], [4], [5], [6], [7], [8]