Intact proinsulin Laboratory research

General Information

Proinsulin It is synthesized in the β cells of the pancreas and in this way an insulin supply is created. It is actually an insulin precursor molecule, which in turn is the most important regulator of carbohydrate metabolism and ensures the uptake of glucose by cells.

Most of the synthesized proinsulin is broken down into insulin and C-peptide, which are secreted into the blood in equal amounts. About 15% of proinsulin enters the bloodstream in unchanged form. Like insulin and C-peptide, blood proinsulin reflects the condition of pancreatic β-cells. Proinsulin level measurement is used in the diagnostics of pancreatic β-cell tumors (insulinoma). Most insulinomas show an increase in the concentration of insulin, C-peptide and proinsulin, but in rare cases only an increase in proinsulin levels may be observed.

Proinsulin has a much lower biological activity (approximately 1:10) and a longer half-life (approximately 3: 1) than insulin. Despite the low biological activity of proinsulin, an isolated increase in its level can lead to hypoglycemic conditions, in malignantly transformed β cells, the ratio of synthesized hormones is shifted to proinsulin. In insulinomas, the proinsulin / insulin ratio is over 25%, sometimes up to 90%. Elevated concentrations of proinsulin may be observed in patients with renal insufficiency, cirrhosis, hyperthyroidism.

Proinsulin levels may increase significantly during PC1 / 3 convertase deficiency. In this case, the metabolism of peptide hormones is altered. People with deficiency of this enzyme, regardless of race, are characterized by red hair, obesity, infertility, adrenal insufficiency, low blood insulin levels, and cortisol deficiency.

When should we take a test for proinsulin?

PC 1/3 marker of insulinoma, enzyme convertase deficiency:

• Diagnosis of hypoglycemic conditions;
• Suspicion of insulinoma;
• Assess the functional status of pancreatic beta cells;
• Suspicion of convertase PC 1/3 deficiency;
• Evaluation of insulin resistance and determination of therapeutic decision in type 2 diabetes.

How to prepare for the test?

A test is required on empty stomach .

Research material

Venous blood

Possible interpretation of the results

Proinsulin levels are elevated:

• Insulinoma;
• Convertase deficiency PC1 / 3;
• Type 2 diabetes;
• Familial hyperproinsulinemia;
• Insulin-producing tumors;
• Chronic renal failure;
• Hyperthyroidism;
• cirrhosis of the liver;
• Severe hypoglycemic hyperinsulinemia

Elevated proinsulin levels indicate a far-reaching state of pancreatic beta cell depletion and represent a highly specific marker for insulin resistance.

It can be used as a therapy selection marker for type 2 diabetes: medications that stimulate insulin secretion, substances that increase tissue sensitivity to insulin (insulin sensitizers), or insulin therapy.

Proinsulin levels are impaired:

• Type 1 diabetes