The December 2011 issue of insulin Dependent Diabetes Trust (IDDT) Newsletter had some interesting thoughts about C-Peptide.
It is important first of all, to know that human and analogue insulins do not contain C-Peptide because they are made by genetic modification in a lab. C-Peptide is release from the pancreas when insulin is released.. People with type 1 Diabetes are deficient in C-Peptide as well as insulin. C-peptide blood testing is being used to determine how much, if any, insulin is being produced by an individual’s pancreas.
It had been assumed that “C-Peptide had no function, but in recent years it has been discovered that C-Peptide binds to the surface of certain cells and activates their signaling mechanism in different ways.” Some studies suggest that C-Peptide may protect the kidney from diabetes-related kidney disease. Diabetes UK is funding C-Peptide research at Leicester University that will “look more closely at the functions of C-Peptide and see if this produces any new approaches to protect against diabetes-related complications. This might lead to adding C-Peptide to insulin treatments.” Although people with type 2 diabetes may have C-Peptide, it is possible that they may be resistant to its actions.
Here are some excerpts from a study published in 2008 in Science/Technology
You can read the whole article at: http://pubs.acs.org/cen/science/86/8602sci1.html"Called C-peptide, this 31-amino-acid peptide is cleaved from the insulin precursor during synthesis of insulin, a peptide hormone that helps cells absorb glucose from the bloodstream. For a long time, researchers thought C-peptide had minimal biological activity, and they dismissed it as a by-product of insulin production. Because C-peptide is secreted at the same concentration as insulin, it has been used as a marker for endogenous insulin secretion and the health of insulin-producing pancreatic beta cells."
"But C-peptide may play a larger role than as just an insulin marker. In recent years, scientists have shown that C-peptide has beneficial effects in patients with type 1 diabetes, including improved kidney function, nerve function, and blood flow. Researchers hope that administration of C-peptide might help alleviate some complications of type 1 diabetes."
SOME PEOPLE have been skeptical about a beneficial role for C-peptide because many patients with early-stage type 2 diabetes have elevated levels of C-peptide. Dana A Spence, Chemistry Professor at Michigan State University thinks that is because the red blood cells of diabetic patients are stiffened. "We have data showing that when the cells get stiff, the C-peptide doesn't work. If the C-peptide doesn't work and it's not facilitating glucose transport into the red cells where it is consumed through glycolysis, one may become hyperglycemic," he says. "You always hear people talking about insulin resistance, but I also think people may be C-peptide resistant."
The study is "a significant contribution to our understanding of C-peptide biology," says Anders Sima, a professor of pathology and neurology at Wayne State University, in Detroit, who studies C-peptide. The findings "may have an impact on future development of C-peptide formulations for pharmaceutical purposes."
"Scientists don't know how C-peptide exerts its beneficial effects. Spence and colleagues at Michigan State University have found a clue to help solve that mystery. In assays where they combine C-peptide with isolated red blood cells from diabetic patients, they find that C-peptide facilitates glucose clearance and causes red blood cells to release adenosine triphosphate (ATP), a known stimulus for the blood vessel dilator nitric oxide (Diabetologia 2008, 51, 175). C-peptide causes these effects by activating the GLUT1 transporter, a protein that shuttles glucose across cell membranes."