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Test-Category
ELISA
Pack size
96 Tests
Standard concentrations included in the kit
1.5-100 pmol/l
Possible sample matrix and volumes
| Plasma | 100 µl |
| Serum | 100 µl |
Incubation periods
Indications
Regulatory Status
Proinsulin is formed in the β-cells of the pancreatic islets of Langerhans as preproinsulin. By splitting off the signal peptide, proinsulin is formed at the rough ER, which is ultimately cleaved at the Golgi apparatus to insulin and C-peptide. Both hormones are secreted in equimolar amounts.
Intact proinsulin was identified as a highly specific, indirect diagnostic marker of insulin resistance in patients with type 2 diabetes mellitus. This was achieved for the first time through the use of a new specific immunoassay for intact proinsulin (Human Intact Proinsulin ELISA Kit), as only this test can detect the current secretion state of the β-cell.
The joint determination of fasting insulin and fasting intact proinsulin allows a pathophysiological staging of type 2 diabetes based on β-cell secretion. In stage I, there is only a temporal disturbance of secretion, whereas in stage II the increasing insulin resistance is compensated by a corresponding increase in insulin secretion. If the cleavage capacity of the β-cell is overtaxed (stage IIIa), the proportion of proinsulin and its partial cleavage products in the plasma continues to increase. This secretion pattern remains almost unchanged even in the secondary failure of the β-cells (stage IIIb).
Due to the influence of increased proinsulin levels on fibrinolysis and adipogenesis, it seems sensible to adjust the therapy to the β-cell dysfunction. Prospective studies have shown that intervention with exercise, metformin, glitazones or insulin leads to sparing of the β-cell and a decrease in intact proinsulin levels, whereas this was not observed with sulfonylureas.
