C Peptide Fasting Test

The amount of C peptide in the blood is the measure of insulin production in the blood. Hence, to see if insulin production is normal or to investigate the cause of high blood sugar, C peptide is measured.

Your doctor would recommend C Peptide test for you if he sees the signs of type 1 diabetes in you. The symptoms include:

• Increased thirst
• Frequent urination
• Intense hunger
• Sudden weight loss
• Irritability and mood swings
• Fatigue and weakness
• Blurred vision

Insulin is a protein produced by the pancreas, and is essential in controlling sugar level in the body. C-peptide is a substance, a short chain of amino acids, which is released when insulin is produced by the pancreas.

This test is done:
- To diagnose the cause of hypoglycaemia.
- To differentiate between type 1 and type 2 diabetes
- To manage diabetes in patients undergoing treatment
- To monitor treatment efficacy in patients with pancreatic tumour. 

The test measures the levels of C-peptide in the blood during fasting state. 

The test requires a blood sample. A tourniquet (elastic) band is placed tightly on the upper arm. The patient is then asked to make a fist. This helps in the build-up of blood filling the veins. The skin is disinfected before needle insertion and the blood sample is collected in vacutainer. 

Increased levels may occur in insulinomas, in chronic renal disease and cirrhosis. Increased C-peptide levels also rule out exogenous insulin administration. 
Decreased levels may occur in insulin-dependent diabetes. C-peptide levels show variation with time, food intake and insulin administration. 
 

The C peptide test, or the C peptide blood test, is a diagnostic procedure that measures the level of C-peptide in the blood or urine, which directly reflects the amount of insulin produced by the pancreas.

The normal range for C-peptide levels is typically between 0.5 and 2.0 nanograms per millilitre (ng/mL) or 0.17 to 0.83 nanomoles per litre (nmol/L), although slight variations may occur between laboratories.

The C peptide test detects the level of C-peptide in the blood or urine, which serves as a direct indicator of insulin production by the pancreas. By measuring C-peptide, healthcare providers can assess pancreatic function, differentiate between type 1 and type 2 diabetes, and diagnose conditions such as hypoglycemia due to an insulinoma or excessive medication use. While C-peptide itself does not affect blood sugar levels, it provides valuable insights into the body's insulin production, helping healthcare professionals make informed decisions regarding diagnosis and treatment.

C peptide test reports provide important insights into insulin production by the pancreas. Abnormal C-peptide levels can point to various underlying conditions. Elevated levels may indicate insulin resistance, type 2 diabetes, an insulinoma, or kidney disease, suggesting excess insulin production. Conversely, low levels may signal type 1 diabetes, advanced type 2 diabetes, or the need for insulin therapy, indicating insufficient insulin production by the pancreas.

A healthcare provider can interpret C peptide test results in the context of the patient's overall health to determine the best course of action, which can include additional tests, medication adjustments, or lifestyle changes.

A positive C peptide test result indicates high insulin levels, which could highlight conditions like insulin resistance, type 2 diabetes, or an insulinoma. It indicates that further evaluation is required to determine the underlying cause and determine the best course of treatment.

While the C peptide test does not directly diagnose diabetes, it helps differentiate between type 1 and type 2 diabetes and monitors the effectiveness of diabetes treatments. Other tests, such as blood glucose or A1c tests, are used for diabetes diagnosis.

The C peptide test, typically involving a blood sample, carries minimal risks, such as a slight sting or pinch from the needle and a small chance of bruising at the site of the blood draw. Urine tests have no known risks.

The benefits of the C peptide test include differentiating between type 1 and type 2 diabetes, assessing insulin production, diagnosing and monitoring conditions like hypoglycemia and insulinoma, guiding diabetes treatment decisions, and evaluating the effectiveness of diabetes medications

The frequency of C peptide test depends on the individual's health condition and the recommendations of the healthcare provider. It may be ordered periodically to monitor changes in insulin production, especially in patients with diabetes or those being treated for conditions affecting insulin levels.

Yes, fasting for 8-12 hours is typically required before a C-peptide fasting test. It's also important to inform your doctor about any medications you're taking, as they may influence the test results.

C peptide test results are generally available after 6 hours, although this may vary depending on the healthcare provider and the time/day the sample is collected and processed.