C-peptide test is a medical test which helps determines how much insulin the pancreas is producing.
C-peptide test measures insulin-connecting-protein called C-peptide in the blood.
Questions and simple answers about c-peptide test requirements and needs as well as the general medical terms related to the C-peptide lab test.
Insulin C-Peptide, Proinsulin C-Peptide; C-Terminal Insulin, Connecting peptide, and serum C-peptide.
No, C-peptide is a kind of connecting proteins, as c-peptide role is to connect insulin units at the beginning of manufacturing insulin inside pancreas beta cells.
But, Insulin is a hormone helps the body cells use insulin.
So, what is C-peptide in the blood test? or
C-peptide is a pancreatic protein which is found in equal amounts to insulin.
C-peptides are protein fragments derived from endogenous insulin only but not exogenous insulin.
The pancreas produce a chemical called proinsulin which consists of equal amounts of insulin and c-peptide.
Insulin helps the body control the amount of sugar in the blood via linking to glucose units and transport it to the cells.
The letter “C” stands for “connecting” protein between insulin units, the complete story below.
For many reasons doctors were preferring to measure the insulin level indirectly through c-peptide test level.
C-peptide and insulin are produced from pancreas at the same rate. so that, C-peptide is a useful marker of insulin production.
But why doctors prefer to test for c-peptide more than insulin itself, more underlying causes:
Testing for C‑peptide is not useful for the routine monitoring of diabetes millitus,
however c-peptide test is a valuable tool when taking therapeutic decisions which are essential for an optimal long‑term metabolic control.
The reasons why to do c-peptide test include:
C-peptide test can be done from plasma ( a blood sample) or urine sample.
You have to fast before c-peptide blood test about 12- 16 hours, and the second sample is drawn 2 hours after a meal.
Fasting requires that you to not eat or drink anything but water before the test.
The preparation needed for the insulin C-peptide test includes that you stop biotin consumption for at least 72 hours before the sample collection at the lab.
The complete list: 6 to 12 hr fasting blood test list, fasting before blood test explained
The price may reach $69.00 in US or around £160 in UK.
Wait time: about 1-2 days if you have the test in some laboratories , while advanced labs may consume one hour to finish c-peptide testing procedures.
However, the c-peptide test time is about 15 to 60 minutes.
Fasting: 0.9 – 7.1 ng/mL
Non fasting c peptide range
PP: 2.73 – 5.64 ng/ml
In urine: 2.5 – 249 μg/day
The next table conclude the conversions of serum C-peptide normal ranges into many different measuring units.
The laboratory units used below: pmol/L, nmol/L, ng/mL, ng/dL, ng/100mL, ng%, ng/L, µg/L
|Unit||Fasting lower value||Fasting higher value||Post-prandial lower limit||Post-prandial higher limit|
* We recommend using SI units when reporting clinical laboratory results.
μg stands for micro-gram (ug).
ng stands for nano-gram.
Do you know: What does reference range means?
C peptide results interpretation depending on the medical conditions.
Also see another article about how to deal with 10 Tips For Abnormal Blood Test Results
The normal C-peptide result is any value lies between the normal limits in the table above.
When c-peptide reading is within the expected healthy ranges it’s said that the pancreas is working well to produce sufficient insulin for body energy.
Normal c-peptide tells that you have normal insulin levels and you will not develop insulin-dependent diabetes.
Blood test results with normal c-peptide may or may not show normal glucose level, that’s because the glucose may be high due to another causes other insulin insufficiency.
High c-peptide will cause high insulin levels and low glucose (hypoglycemia) until the pancreas beta cells destroy themselves.
then glucose will be elevated again because there’s no insulin again from dead pancreas.
Elevated C‑peptide levels is a result of increased β‑cell activity such as in hyperinsulinism, renal insufficiency, and obesity.
Blood test results may show high C‑peptide levels and increasing hyperlipoproteinaemia and hypertension too.
An elevated c-peptide level may be due to one or more of the following:
What causes high C peptide levels are:
What does it mean when insulin levels are low?
If a person’s body makes too little insulin or the cells become resistant to its effects, cells starve.
Low c-peptide means low insulin level which in turn means insufficient glucose transported to the body cells while the blood stream is full with unused glucose.
Low C-peptide comes from inflammation of the pancreas or necrosis (death of pancreatic cells),
also the removal of pancreas is the obvious cause of low c peptide levels in the blood.
The causes of low c-peptide:
Low c-peptide is a result of low insulin production after beta cells inflammation,
people with balanced diet and high carbs. may still show normal blood glucose even after c-peptide and insulin levels decreased.
Normal glucose mean your body still be able to produce enough insulin to control the glucose in the blood, but what if the c-peptide is high, does it mean high insulin too?
C-peptide and insulin are two faces from the same coin, they come high or low at the same time.
If the diagnosis is type 2 DM at the beginning then your c-peptide and insulin should become higher over the time to overstimulate cells to absorb more sugar.
But, over the time and with poor diabetes management the hyper secretions from pancreas will cause damage to the pancreas cells and lead to no insulin nor c-peptide production, and the sugar back to the elevated levels.
If you’re taking insulin injections (exogenous insulin) your insulin level may be in the target values or be higher a bit,
while the c-peptide is not found in the exogenous insulin preparations it will remain on the normal.
For persons with low c-peptide,
You should know that the goal from c-peptide test is for indirect measurement of insulin levels thus we should seek for increasing insulin when c-peptide is low.
However, the beta cells in T1 will still adjust the amount of insulin/c-peptide production upon the amount of elevated glucose.
Some recent studies suggest that the s-peptide is an active protein and has a biological role in diabetes management.
There is evidence that C‑peptide replacement accompanied with administering insulin, may prevent the development or retard the progression of long-term complications in type 1 diabetes mellitus.
Guide for how to increase c-peptide levels and treat hypoglycemia that may come from
excessive supplementation of insulin, alcohol consumption, inherited liver enzyme deficiencies, liver or kidney disease, or by insulinomas.
Keeping glucose levels stable will also regulate insulin levels and stop c-peptide secretions.
Many patients ask me what if my c peptide is high and what to do if my c-peptide test results came high
Ask your doctor about some drugs act against pancreas cancerous cells to stop spreading.
Eating an insulin resistance diet may help reduce high cpeptide and insulin levels:
People need continuous assessment of β‑cell function, also may test c-peptide in urine rather than in blood, also it’s useful in the conditions below:
Useful to see: Urine Sugar Levels Chart, What Does Sugar in Urine Mean?
References for Diabetes patients:
More to come:
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