What are the other names for this test?

Proinsulin C-peptide, Insulin C-peptide, Connecting Peptide Insulin

What is a C-peptide test?

A C-peptide test helps to determine the c-peptide levels in your blood or urine. This test observes how well your body is developing insulin amounts. A c-peptide test may detect the reasons for low blood glucose.
Insulin is a hormone produced by the pancreas. Pancreas is an organ and gland that produces enzymes to make better digestion. It also releases hormones that regulate and control the sugar amount in your blood vessel. Insulin moves blood glucose or sugar to your cells to develop energy for your body.
C-peptide develops by your pancreas when insulin is in the production phase. Both c-peptide and insulin come into your bloodstream within the same duration and quantities. C-peptide remains in your blood longer than insulin and does not show any side effects on your blood sugar levels. It is the reason c-peptides can measure in an accurate way.

What is the purpose of this test?

A c-peptide test is a routine test that helps to diagnose insulin disorders. This test may use to:
 

• See whether your body has the ability to produce the required insulin.
• Observe if you are dealing with insulin resistance.
• Monitor treatment if you are already experiencing insulin problems or diabetes.
• Identify which type of diabetes you have, either type 1 or 2. In a few cases, it is difficult to know the type of diabetes. A c-peptide test may be required if you are uncertain about diagnosing diabetes after three years.
• Screens for blood glucose disorders
• Determine the reason for hypoglycemia (Low blood sugar)
• Monitor treatment for a pancreas tumor, also known as insulinoma. This condition happens very rarely in people. These tumors produce large insulin amounts and lead to low blood sugar.

When do I need to take this test?

You may need a c-peptide test if you are dealing with repeated hypoglycemia (Low blood sugar) and high insulin. This test helps to differentiate between your body's insulin and the other sources of insulin. Signs and symptoms of hypoglycemia, such as:
 

• Increased hunger
• Sweating
• Confusion
• Blurry vision
• Seizures and loss of awareness in extreme cases
• Missing heartbeat (Palpitation)

If you see the above symptoms, you can take the c-peptide test at a low price.
Your healthcare provider may recommend this test if you already have experience with an insulinoma. This test can monitor how well the treatment is going and find tumor repetition. You may order this test if your provider wants to see if more insulin injections are needed if you have diabetes.
A c-peptide test often helps maintain type 1 diabetes. This test may also give benefit you if you are dealing with type 2 diabetes and requires insulin amounts.

What is the procedure for this test?

The sample depends on the test type your provider recommends to you. You may need to provide a blood sample or a urine sample. For the blood test, the following are the steps of a c-peptide that include:
 

• Your provider will ask you to stay relaxed and calm before the test.
• Take a seat in front of your provider and remove your cloth from one of the arms.
• A small needle will inject into the vein in your arm.
• Your blood sample will collect in a test tube
• A little discomfort or pain may happen during the test or at the time of injection of the needle.
• Regular activities may resume after the test.
• This test will finish within five minutes.

How do I need to prepare for this test?

A c-peptide test does not need any specific preparation. You may eat or drink if you have only this test. But when your provider asks for other blood tests, you may need to fast for at least several hours. You can inform your provider about medicines, supplements, or vitamins you use. Do not avoid your medication without the prescription of your doctor.

Are there any risks involved in this test?

A c-peptide test contains low risks when you give a blood sample to your provider. Vein differs from person to person. You may experience low risks when the needle injects into your vein, include
 

• Infection
• Bruising
• Extreme Bleeding
• Slight pain
• Hematoma (Deposition of blood under the skin)

 
You may feel discomfort during swabs collection from your throat or nose.

What do the test results indicate?

The recommended range of c-peptide test results lies between 0.5 to 2.7 ng/mL (Nano grams per milliliter). The test results may vary on various factors, such as gender, sex, family history, medical history, and others. Sometimes the test results may also slightly change among laboratories due to the use of different references for measurement. You can consult your test result with a professional healthcare provider here.

High c-peptide levels may indicate your body produces large insulin amounts. The following are the reasons that indicate high insulin levels:
 

• Cushing’s syndrome
• Insulinoma (pancreas tumor)
• Kidney failure or damage
• Type 2 diabetes
• Low potassium levels in the blood

Low c-peptide levels may indicate your body does not produce the required insulin. The following are the conditions that lead to low insulin levels:
 

• Type 1 diabetes
• Type 2 diabetes (In a few cases)
• Addison disease
• Intake of high insulin amounts for treatment of diabetes. If you take insulin higher compared to the requirement, this may resist producing insulin by your pancreas)
• Extreme infection
• Liver disease

C-peptide levels reduce if you have taken treatment for an insulin-producing pancreas tumor, which shows that the treatment is working in a proper way. Whenever the tumor returns back, it will lead to high c-peptide levels.

What additional tests do I need along with this test?

Your healthcare provider may suggest more tests to see the blood glucose levels and other related substances, including:
 

• Diabetes Glucose test: This test will determine the glucose amount in the blood.
• Insulin assay: This test helps to determine insulin levels.
• Glucagon test: This test helps to determine another hormone produced by your pancreas.
• A1c test:  Also known as a glycosylated hemoglobin blood test. This test can determine your blood sugar levels for the past three months.

What factors may affect the test result?

C-peptide levels may increase if you are a person having diabetes and taking insulin for it. Damaged kidneys may also show altered c-peptide levels. The timing of the test is another factor for the c-peptide level.