Proper Procedure for Checking C-Peptide

A C-peptide test can help diagnose several diseases.

After a diagnosis of diabetes, an insulin C-peptide blood test helps determine the type of diabetes -- 1 or 2. The test also helps diagnose the cause of hypoglycemia (low blood sugar) and whether a pancreatic tumor was completely removed. The test procedure can vary between children and adults.

Adults

After the injection site is sterilized, an elastic band is tightened around the upper arm, and a needle is inserted into a vein. The elastic band is removed as blood is collected in a glass tube. Once the blood has been drawn, a bandage is put over the site to stop any bleeding. Fasting may be necessary prior to the test.

Children

Blood may be collected from infants and young children by first cleaning the skin with an antiseptic, then pricking the skin and collecting the blood in a glass tube or onto a slide. A bandage is then applied if there is bleeding.

Considerations

Certain factors can affect the outcome of a C-peptide test. Medications for diabetes, and diuretics, corticosteroids and birth control pills can skew test results. Kidney failure, obesity and alcohol consumption might preclude a patient from having his C-peptide level checked, because the results would not be accurate.

References

• MedlinePlus: Insulin C-peptide
• Lab Tests Online: C-Peptide
• University of Michigan Health System: C-Peptide