C-Peptide Test: Procedure, Purpose, Results, and Normal Range

What Is C Peptide Test?

The C-peptide test determines the level of the C-peptide in the blood or urine.C-peptide is a peptide that contains 31 amino acids. When proinsulin is broken down to make insulin, C-peptide is secreted from the pancreatic beta cells. It is a substance that is formed when insulin is generated and released into the body.

Insulin is a hormone that is produced by the pancreas. It makes it easier for blood glucose (blood sugar) to get into the body's cells, where it can be used as fuel. This maintains healthy amounts of blood sugar in the body. The pancreas makes C-peptide while producing insulin. Insulin and C-peptide both reach the bloodstream simultaneously and in equal amounts. Although C-peptide does not influence blood glucose levels, it is simpler to measure precisely because it remains in the blood for a longer period of time than insulin.

Also, the half-life of C-peptide is three to four times longer than that of insulin and is primarily eliminated through the kidneys.

Why Is C Peptide Blood Test Done?

The C-peptide test is used to determine the presence of type 1 diabetes, which occurs when the immune system attacks and kills pancreatic cells, or type 2 diabetes, which takes place when the body does not use insulin as effectively as it should. It reveals how effectively the body produces insulin, which transports glucose from the blood to the cells. The doctor may use the test to determine whether or not an individual has to take insulin to manage their condition. Although it can provide a reading to aid in treating diabetes, physicians do not use it to truly diagnose the condition. In addition, because only insulin that is produced by the pancreas is linked to the C peptide, this test can distinguish between the insulin the body produces and the insulin individuals take.

When Is C-Peptide Test Advised?

The physician might advise getting this test done for the following conditions:

• Hypoglycemia (low blood sugar) has been identified in a person, but the exact cause is unknown.

• When a patient has diabetes and uses insulin, their doctor is planning to change the prescribed treatment regimen.

• When a patient has type 2 diabetes, the doctor wishes to determine whether the patient needs to start taking insulin.

• When an individual is diabetic and has hypoglycemia, which can result from taking too many diabetes medications.

• When a pancreatic tumor has been identified in the patient (insulinoma). The disease and therapy can be tracked with the aid of a C-peptide test.

What Is the Purpose of the C-Peptide Test?

The C-peptide test can diagnose the following conditions in the body:

1. It can diagnose the source of the hypoglycemia (low blood sugar). High insulin levels have been related to some types of hypoglycemia. Whether too much insulin is contributing to hypoglycemia can be determined by a C-peptide test. Hypoglycemia may have several reasons, including:

• A renal or liver disorder.

• Malnutrition.

• Excessive alcohol consumption without meals.

• Having a pancreatic tumor.

• Impacts of some diabetes medications, such as insulin.

1. The amount of insulin that the pancreas produces can affect treatment options for patients with type 1 or type 2 diabetes. This test can give an idea about how much insulin the pancreas is producing. Even if people are taking insulin medicines for their diabetes, a C-peptide test can still yield an accurate measurement of insulin production by the pancreas cells. This is so because the amount of insulin the pancreas produces affects the amounts of C-peptide. The insulin that diabetic patients take has no effect on them.

2. To diagnose the presence of an insulin-producing pancreatic growth known as an insulinoma. Also, they monitor the treatment of insulinoma. These tumors overproduce insulin, which lowers blood sugar levels. They can typically be removed through surgery and are mostly non-cancerous.

3. It can diagnose the type of diabetes, whether type 1 or type 2 in a patient. If type 1 diabetes is diagnosed, this test will indicate how much insulin the pancreas is still producing. If type -2 is diagnosed, it can determine whether a patient with type 2 diabetes needs to start taking insulin.

What Is the Preparation Needed Before the C-Peptide Test?

One may need to fast (not consume or drink anything) for 8 to 12 hours prior to a C-peptide blood test. Before the test, the patient should also tell the doctor about all medications and supplements they are taking.

How Is the C-Peptide Test Performed?

Mostly, the sample for the C-peptide test is taken from blood. However, sometimes a urine sample can also be used.

Blood Sample: Using a tiny needle, a medical professional will draw blood from a vein in the arm for blood sample collection. After the insertion of the needle, a small quantity of blood will be gathered in a test tube or vial. When the needle passes through or out, the patient might experience slight pain. Normally, this takes less than five minutes.

Urine Sample: The patient is instructed to urinate into the container as directed. The patient has to collect all of their daily output for a 24-hour urine sample.

What Do the Results of the C-Peptide Test Indicate?

The reports of the C-peptide test come within a few days. The normal range of C-peptide ranges from 0.5 to 2.0 nanograms per milliliter. When the body produces more insulin than normal, these levels can increase. When the body produces less than it should, the level comes low.

High C-peptide Levels: The levels may come high in reports due to following conditions:

• A pancreatic tumor, insulinoma.

• A kidney disorder.

• When the patient has insulin resistance.

• A low level of potassium in the bloodstream.

• Cushing's syndrome (a hormonal disorder that arises when the body consistently produces excessive amounts of the hormone cortisol).

Hence, the high levels of C-peptide indicate the presence of the above conditions.

Low C-peptide Levels: Low C-peptide levels could indicate:

• Individuals have type 1 or type 2 diabetes with a damaged pancreas.

• As a result of insulin injections, the pancreas is suppressing insulin production.

• The pancreas ceases producing insulin when the blood sugar is low, or it does not produce any as a result of taking insulin.

• The size of the insulinoma has decreased due to treatment. This indicates that treatment for insulinoma is working well.

• A severe infection.

• Addison disease (a hormonal disorder, in which adrenal glands can not produce sufficient cortisol and aldosterone hormone).

• Liver disease.

Conclusion:

Diabetes cannot be identified using a C-peptide screen. The type of diabetes can be identified. Diabetes is detected and diagnosed using additional procedures like blood glucose and urine glucose analysis. This test is also known by other names like the insulin C-peptide test, connecting peptide insulin, or proinsulin C-peptide.