C-Peptide
Private C-Peptide blood test in London for £139, measuring endogenous insulin production with results in around 1 business day.
Turnaround time
1 business day
Biomarkers count
1
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Overview of the C-Peptide
The C-Peptide blood test measures C-peptide, a substance released when the pancreas produces its own insulin.
Insulin begins life inside pancreatic beta cells as a larger molecule called proinsulin. When proinsulin is divided, insulin and C-peptide are released into the circulation in approximately equal amounts.
The test contains 1 biomarker: C-Peptide.
Because injected pharmaceutical insulin does not contain C-peptide, this marker provides useful information about how much insulin the person's own pancreas is producing.
C-Peptide can therefore contribute to diabetes classification, assessment of remaining beta-cell function and selected investigations of unexplained hypoglycaemia.
A low C-peptide concentration in the presence of raised glucose can indicate significant loss of pancreatic insulin production.
A higher C-peptide result can occur when the pancreas is producing substantial amounts of insulin, including in insulin resistance and many cases of type 2 diabetes.
Kidney function matters when interpreting the result because C-peptide is cleared substantially through the kidneys.
C-Peptide should usually be interpreted alongside the blood-glucose concentration and the reason the test was requested.
What Does the C-Peptide Test Check?
This test measures 1 biomarker.
C-Peptide
Measures a peptide released alongside the body's own insulin, providing information about pancreatic beta-cell insulin production.
Who May Benefit From the C-Peptide Test?
C-Peptide may be useful when the amount of insulin being produced naturally by the pancreas needs to be assessed.
People with diabetes where the type is uncertain - C-Peptide can help establish whether substantial endogenous insulin production remains.
People being investigated for type 1 diabetes - Low C-peptide can support evidence of significant beta-cell failure when interpreted with glucose and diabetes autoantibodies.
People with type 2 diabetes requiring assessment of pancreatic function - The test can show whether meaningful endogenous insulin secretion remains.
People using injected insulin - C-Peptide can still measure the body's own insulin production because pharmaceutical insulin does not contain C-peptide.
People with unexplained hypoglycaemia - Measurement during a documented low-glucose episode can help determine whether endogenous insulin secretion is inappropriately high.
People with suspected insulin resistance - Increased endogenous insulin secretion may be reflected in higher C-peptide concentrations.
People following pancreatic surgery or significant pancreatic disease - C-Peptide may help assess remaining beta-cell function.
People specifically referred for diabetes classification - The result can provide useful information when treatment depends on understanding endogenous insulin production.
How to Prepare
Do not stop insulin or another diabetes medicine simply to influence the C-Peptide result.
The blood-glucose concentration at the time of sampling is central to meaningful interpretation.
Symptoms and Reasons to Consider the C-Peptide Test
C-Peptide is not ordered because of one specific symptom. It is usually considered when symptoms or glucose abnormalities raise questions about insulin production.
Frequent urination - Increased urination can occur when blood glucose is significantly elevated.
Persistent thirst - Excessive thirst can accompany hyperglycaemia and may prompt diabetes investigation.
Unexplained weight loss - Significant insulin deficiency can lead to weight loss despite normal or increased food intake.
Unexplained high blood glucose - C-Peptide can help determine how much endogenous insulin is being produced when hyperglycaemia is present.
Repeated episodes of low blood glucose - C-Peptide collected during documented hypoglycaemia can contribute to investigation of excessive endogenous insulin secretion.
Shaking or sweating during low blood glucose - Adrenergic symptoms can occur during hypoglycaemia and may prompt metabolic investigation.
Confusion or weakness during low blood glucose - Neurocognitive symptoms can occur when glucose falls significantly.
Uncertainty about type 1 versus type 2 diabetes - C-Peptide may help clarify the degree of insulin deficiency.
Unexpected changes in insulin requirements - Altered treatment needs may occasionally prompt assessment of remaining pancreatic insulin production.
These symptoms are not specific to abnormal C-Peptide and can occur for many other reasons.
Severe hypoglycaemia causing confusion, loss of consciousness or seizures, or severe hyperglycaemia associated with vomiting, dehydration, deep breathing or marked illness requires urgent medical assessment.
How to Book Your C-Peptide Test
Booking your C-Peptide blood test with London Blood Tests is straightforward.
Choose the C-Peptide
Select the individual C-Peptide blood test.
Select your sample collection option
Choose an in-clinic blood draw or professional home or hotel phlebotomy.
Attend your appointment
A trained healthcare professional collects the required venous blood sample under the advised fasting or timing conditions.
Laboratory analysis
Your serum is analysed for C-Peptide concentration.
Receive your results securely
Your authorised result is delivered securely for interpretation with glucose and other diabetes-related results.
When Will I Receive My Results?
The current expected turnaround time is approximately 1 business day after your sample reaches the laboratory.
Laboratory quality checks or repeat analysis may occasionally extend reporting.
Understanding Your Results
A lower C-Peptide result indicates lower endogenous insulin production.
Very low C-Peptide in the presence of elevated blood glucose can support significant pancreatic beta-cell failure.
A normal result confirms measurable endogenous insulin production but must be interpreted according to the glucose concentration at the time.
Higher C-Peptide can occur when the pancreas is producing increased amounts of insulin, including in insulin resistance and many cases of type 2 diabetes.
When hypoglycaemia is being investigated, C-Peptide should be interpreted together with glucose and insulin.
Kidney impairment can raise circulating C-Peptide because renal clearance is reduced.
There is therefore no single C-Peptide number that can be interpreted meaningfully without clinical context.
Why Book With London Blood Tests?
Private C-Peptide testing in London - Access targeted assessment of endogenous insulin production.
Useful for diabetes classification - C-Peptide can help establish how much pancreatic beta-cell function remains.
Suitable for people taking insulin - Injected insulin does not contain C-Peptide.
Relevant to hypoglycaemia investigation - The marker can contribute to specialist assessment when collected under the correct conditions.
Fast results - Current turnaround is approximately 1 business day.
Trusted UK laboratories - Samples are processed through established professional laboratory services.
Clinic and home collection options - Professional phlebotomy can be arranged.
Clear pricing - The C-Peptide test costs £139.
Private C-Peptide Blood Test in London
London Blood Tests provides private C-Peptide testing in London for people requiring assessment of endogenous insulin production.
The test costs £139 and measures one biomarker: C-Peptide.
It may be particularly useful during diabetes classification, assessment of residual pancreatic function or specialist investigation of hypoglycaemia.
Results are expected approximately 1 business day after laboratory receipt.