Quite often, doctors prescribe an analysis that helps determine the amount of a substance such as a C-peptide. In diabetes mellitus, this study sometimes gives more accurate results than analysis for sugar or insulin levels. Of course, patients are interested in additional information.
What is a C-peptide study for diabetes? How are samples taken? Do I need to somehow specially prepare for the procedure? How to decipher the results? Many are looking for answers to these questions.
What is a C peptide?
In modern practice, a C-peptide blood test is often performed. In diabetes mellitus, the results of this study are extremely important. But first, it’s worth learning more about what this substance is.
As is known, proinsulin is synthesized in the microsomes of beta cells of pancreatic islets. This substance is devoid of biological activity. But in response to increased glucose levels, proteolysis processes start. The proinsulin molecule is cleaved into biologically active insulin and the C-peptide.
This protein molecule is not biologically active. Nevertheless, its amount reflects the rate of insulin formation in the pancreas. That is why it is so important in the diagnostic process to pay attention to peptides. In diabetes mellitus type 2 and type 1, the indicators, by the way, are different.
Indications for the study
When do doctors recommend this study? The list of indications is quite impressive:
- Differential diagnosis of diabetes mellitus of the first and second type.
- Diagnosis of hypoglycemic conditions (for example, if you suspect the presence of insulinoma or an artificial form of hypoglycemia).
- The results of the study help to create the optimal diabetes treatment regimen.
- The procedure is carried out in order to evaluate the function of beta cells in the event that it is planned to interrupt insulin therapy.
- The test helps to study the processes of insulin synthesis against the background of various liver diseases.
- The procedure is prescribed for patients undergoing pancreatic removal (makes it possible to check whether all the cells of the organ were really removed during the operation).
- The analysis is also part of a comprehensive diagnosis of polycystic ovary syndrome.
How to prepare for the delivery of samples?
Proper preparation for the procedure makes it possible to accurately determine the C-peptide in diabetes mellitus. In fact, you just need to follow some simple recommendations:
- blood sampling is performed on an empty stomach (you should refrain from eating for 8 hours or more);
- before the procedure, you can only drink clean water (without sugar and other additives);
- within two days before sampling, you need to give up alcohol;
- do not take medications (if there is still a need to drink pills, then you must inform your doctor about them);
- It is important to abandon physical activity, avoid stress;
- three hours before the procedure, you should stop smoking.
C-peptide blood test for diabetes: how is it done?
In fact, the procedure is quite simple. Peptide analysis for diabetes mellitus involves standard sampling of vein samples. Blood is placed either in dry tubes or in a special gel, after which it is passed through a centrifuge in order to separate the plasma from the formed elements. Next, the samples are frozen, and then examined under a microscope using special chemicals.
Stimulated test
It is worth noting that it is far from always possible to notice changes in the level of a substance such as C-peptide in diabetes mellitus. The norm is often recorded even in patients with an already diagnosed disease. In such cases, a so-called stimulated test is performed.
Before blood sampling, glucagon, which is an insulin antagonist, is injected. However, this substance cannot be administered to patients with high blood pressure, and this is a common complication in diabetics. In such cases, a standard blood sampling is performed, but after breakfast.
By the way, in the ideal case, you need to conduct both a standard and a stimulated test - the only way to count on a reliable result.
Normal blood matter
It is immediately worth noting that the amount of C-peptide is directly related to an increase in the concentration of insulin produced by the pancreas. The most accurate results can be obtained if you take blood for analysis on an empty stomach. The norm ranges from 0.78 to 1.89 ng / ml. By the way, this indicator is the same for men, women and children.
It is worth noting that sometimes to obtain a complete picture, a test for insulin levels is also carried out. Then the doctor calculates the ratio of the level of C-peptide and insulin: if it is less than 1, then this indicates an increase in the secretion of endogenous insulin. In those cases, if the indicator is higher than 1, then it is likely that the hormone was introduced into the body from the outside.
What does an increase in the number of peptides indicate?
The results of a standard analysis can be obtained already 3-4 hours after blood sampling (as a rule, they are given the very next day). And in the medical records of many patients it appears that the level of this protein in their blood is reduced. What does this indicate?
The list of reasons is quite large.
- To begin with, it is worth saying that the C-peptide in type 2 diabetes is increased (it is this factor that is taken into account in the differential diagnosis of diabetes).
- This indicator also increases in the presence of insulinomas (a hormone-active tumor that develops from beta cells of the pancreas), since this neoplasm is accompanied by intensive synthesis of insulin.
- An increase in the amount of C-peptide is observed against the background of progressive renal failure.
- A similar violation of this indicator often develops against a background of liver diseases, including various forms of hepatitis and cirrhosis.
- Male obesity also affects C-peptide levels.
- Long-term administration of hormonal drugs, including glucocorticodes (anti-inflammatory drugs) and estrogens, can enhance insulin secretion (and, accordingly, increase the amount of peptide).
- A high level of C-peptide may be associated with the use of drugs that significantly reduce the amount of glucose in the blood.
- The same picture is observed after transplantation of beta cells or transplantation of a whole pancreas.
- As already mentioned, the amount of peptide depends on the rate of insulin secretion, and this, in turn, is directly related to the level of glucose. An increase in the level of this protein is observed if the patient ate before taking the test.
- The list of causes includes somatotropinoma. This is a benign pituitary tumor that affects the secretory activity of the hypothalamic-pituitary system and affects the functioning of all endocrine glands.
- An increase in C-peptide levels may result from apudoma growth. This tumor is usually formed from islet cells of the pancreas.
Decrease in the level of C-peptide: causes
Many people wonder why this indicator may decline. The reasons may be different:
- C-peptide in type 1 diabetes is reduced.
- The reasons include artificial hypoglycemia, which is associated with the introduction of insulin-containing drugs into the body.
- A decrease in the level of this substance is observed in patients who underwent a radical pancreatic surgery.
Of course, only the attending physician can correctly decipher the test results. An accurate diagnosis always requires additional tests and instrumental studies.
Why is it more preferable to determine the C-peptide for diabetes?
Of course, this procedure is carried out often. Why is determining the level of a substance such as C-peptide for diabetes so much more effective than calculating the amount of insulin itself?
- To begin with, it is worth noting that the half-life in the blood is longer, since insulin breaks down faster. The first indicator is much more stable.
- This procedure allows you to evaluate the rate of synthesis of natural insulin even against the background of the introduction of artificial hormone into the body. Insulin therapy is not a contraindication to the analysis - the results will still be accurate.
- Determining the amount of C-peptide allows you to determine the exact level of insulin even in the presence of autoimmune processes in the body.
What other diseases does this test help determine?
Most often, this procedure is used for the differential diagnosis of diabetes. Nevertheless, the level of C-peptide can fluctuate against the background of other diseases.
For example, this analysis is included in the diagnostic scheme for cases of suspected polycystic ovary syndrome, Cushing's disease, and chronic renal failure. By the way, in the presence of the above diseases, the level of C-peptide is increased.
Peptides and diabetes treatment
A few years ago it was generally accepted that the C-peptide is not functionally active. However, recent studies have shown that this substance has important properties.
The results of clinical trials showed that the introduction of a C-peptide into the patient's body along with insulin significantly reduces the likelihood of complications. For example, among people who injected this protein, cases of neuropathy, nephropathy, and diabetic angiopathy were recorded much less frequently.
By the way, over the past few years, Havinson's peptides have gained particular popularity. Diabetes mellitus is an indication for therapy with the help of such drugs. Of course, such treatment gives some results, but you should not count on full healing. The introduction of peptides (subject to the use of quality drugs) only helps reduce the likelihood of complications.
Today it is not known exactly how C-peptides affect the body. This topic remains open. Still, scientists are actively studying the properties of these protein components and their mechanism of work.
Use preparations containing the above substances can only be with the permission of the attending physician and under close supervision. The use of peptides is not a substitute for traditional therapy, so you can not refuse insulin and other drugs.