C Peptide Test

The pancreas secretes a hormone called insulin. It controls the level of glucose(sugar) in your blood at any given time. It also helps store glucose in your liver, muscles and fats. If your body is not producing enough insulin, it is a sign of Type 1 or Type 2 Diabetes.

The C-peptide test measures C peptides in blood. C peptide is also secreted with insulin in the pancreas. Insulin and C peptide are secreted at the same time and in almost equal quantities in the pancreas. Thus, this test helps in showing how much insulin your body is releasing.

C-peptide has a half-life of 30 minutes and tends to stay in the body longer than insulin. Insulin has a half-life of 15 mins. Therefore, this test is an excellent way to measure insulin levels, especially insulin levels produced by the pancreas and exclude the insulin level in the bloodstream from injected insulin.

A C-peptide test helps with the diagnosis of Type 1 and Type 2 Diabetes Mellitus. The difference between the two is, in Type 1 Diabetes, the pancreas secretes a negligible amount of insulin and negligible C-peptide. Whereas in Type 2 Diabetes, the pancreas secretes insulin, but the body does not use it properly, which causes C-peptide levels to be higher than usual. If the result of the C-peptide test confirms Diabetes diagnosis, treatment should be initiated under expert guidance.

You may require a C-peptide test if your glucose levels are low(hypoglycemia) and show symptoms like irregular heartbeat, uncontrolled hunger, blurred vision, dizziness and excessive sweat.

Also, the test is recommended to diagnose a tumour in the pancreas. Extremely high levels of C-peptide would be suggestive of a tumour. The tumour is known as insulinoma. The C-Peptide test is used to diagnose if your pancreas is to be removed during surgery.

Diabetes Mellitus is common in India due to various possible factors, such as genetic factors associated with lifestyle changes leading to conditions such as obesity. In India, however, Diabetes prevalence is higher even among those with lower weight, suggesting that relatively lean Indian adults with a lower body mass index may also be at risk. As a result, Diabetes is rapidly on its way to becoming a potential epidemic in India. At the moment, there are an alarming 62 million diabetic individuals currently diagnosed with the disease in India.

Other names of the C-Peptide test

        1. Insulin C-peptide test

        2. Connecting peptide Insulin

        3. Proinsulin C-peptide

What does the C-peptide test detect or measure and who is this prescribed for?

The C-peptide test measures the levels of C- peptide in the blood, which helps us to know the status of endogenous insulin in the body.

Generally, a C-peptide Test is ordered if your symptoms indicate Diabetes Mellitus. Some indications of prescribing a C-peptide Test are:

• Your blood glucose levels are higher than average.

1. Greater than 120 mg/dL while fasting or alternatively they are
2. Greater than 200 mg/dL during a random blood test

• Irregular Heartbeat
• Uncontrolled hunger.
• Blurred vision
• Sweating
• Confused state of mind
• Dizziness and Fainting        
• Unexplained weight loss
• Frequent Urination
• Feel lethargic
• Thirsty
• Tingling sensations in extremities

Some disease conditions for which a C-peptide test can be prescribed are:

• Type I Diabetes Mellitus
• Type II Diabetes Mellitus
• Insulinoma

These levels are high when the pancreas secretes high levels of insulin and are low when the insulin secretion is minimal.

High levels of C-peptide indicate:

• A high insulin level means the body has developed resistance to insulin which interprets that your body is not utilising the insulin secreted by the pancreas. (Also, if you have Type 2 Diabetes, your insulin levels may be high.)
• This may also indicate a tumour known as insulinoma, in which the tumour secretes excess insulin.

Low levels of C-peptide indicate:

• You have Type 1 or Type 2 Diabetes, with the pancreas releasing little or no insulin in your body.
• You are taking insulin as your treatment for Diabetes Mellitus and the insulin taken is suppressing the release of endogenous insulin.
• Treatment for insulinoma has worked and the tumour has shrunk.

The results of a C-Peptide test are based on the analysis of a blood sample.

Test Preparation

The C-peptide test is either

1. A blood test that requires fasting for 8-12 hrs. The usual way to collect a blood sample is by drawing it from one of the veins usually, the forearm veins. You may feel a slight prick.
2. For a urine test; you will have to pee into a sample collection container. For a 24-hour sample, you will need to collect the entire urine that you pass in a day.

Test inclusions: What parameters are inclusive?

The C-peptide test includes the following parameter:

1. The range or value of C-peptide secreted by the pancreas in the blood.

C-peptide levels are the only parameters included in this test. They provide information on the secretion of insulin by the pancreas. The C-peptide test does not give a positive or negative result.

How frequently should you take the C-Peptide test?

The C-peptide test may be repeated by the consulting physician to check and evaluate the effectiveness of the Diabetes treatment. Doctors may prescribe a C-peptide test every six months, following a diagnosis of Diabetes Mellitus by an M.D. physician or endocrinologist, to monitor and regulate the dosage. The results of the C-peptide test may help your doctor continue the same treatment or modify the dosage of ongoing medicines.

Hypoglycemia, Type 1 and Type 2 Diabetes Mellitus, Insulinoma