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Embargoed until Tuesday, May 25, 2004

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Breakthrough in diabetes research at WSU:   Study explaining C-peptide’s effect in combating type 1 diabetic neuropathy published in Diabetes

To run a car, you need two types of petroleum products: gasoline and motor oil. If you only use gas, the car will run, but its engine eventually will blow out because the oil isn’t there to lubricate it.

During the past few years, researchers have discovered that a hormone traditionally considered a useless byproduct of insulin production might be the “oil” necessary to help people with diabetes keep their bodies in good running order longer by fending off complications. And now, a Wayne State University School of Medicine study in the June 1 issue of Diabetes explains how this hormone works

Anders Sima, MD, PhD, WSU professor of pathology and neurology, has published a study describing both the molecular aberrations that cause peripheral nerves to break down in rats with type 1 diabetes and how the hormone C-peptide works to alleviate this dysfunction. A study published last year in Diabetes reported that C-peptide had similar results in humans in ameliorating the effects of peripheral neuropathy.

Currently, no therapies exist for diabetic neuropathy, the most common chronic complication of diabetes and one that can lead to loss of sensation, chronic pain, erectile dysfunction, foot ulcers, limb amputation and life-threatening heart dysfunction.

“I’m convinced that C-peptide will make a difference in terms of treatment and prevention,” Dr. Sima said.

Forty type 1 diabetic rats were used in the study along with a control group of 20 non-diabetic rats and 20 rats in the early stages of type 2 diabetes with normal C-peptide levels. In the 20 type 1 diabetic rats that received C-peptide therapy, nerve function was markedly protected from the degenerative effects associated with diabetic complications.

Although nerve function was not entirely normal in the rats that received C-peptide, the study showed three benefits related to the hormone in contrast to type 1 diabetic rats that received no C-peptide: nerve function improved, nerve degeneration was prevented and nerve regeneration was enhanced.

“We may not be able to totally prevent complications, but if we can optimize the circumstances, we can improve quality of life substantially,” Dr. Sima said. “By pushing off the complications 15 or 20 years, you’ve gained an awful lot of ground.”

Diabetes costs in the United States total about $132 billion annually, according to the American Diabetes Association. Much of that cost is attributable to treating complications, Dr. Sima said.

Although type 1 diabetics account for only up to 10 percent of the 18.2 million Americans with diabetes, Dr. Sima is continuing his work to examine the potential benefits of using C-peptide to aid the complications of late-stage type 2 diabetes. Although type 1 and type 2 diabetes are distinctly different in their early stages, C-peptide may be useful in treating complications in people with type 2 diabetes who are insulin dependent.

Proinsulin, a molecule manufactured in the pancreas, is made up of insulin and C-peptide. It has long been known that insulin regulates the body’s blood-sugar levels, but up until recently, scientists believed C-peptide was useless byproduct.

Two years ago, Dr. Sima showed that C-peptide bolsters several effects of insulin, such as gene regulation of growth factors; enhances its neuroprotective effect; and prevents programmed cell death. It does not, however, affect blood-sugar levels.

The next step in proving the efficacy of C-peptide requires at least two Food and Drug Administrative-approved clinical trials. If further research confirms Dr. Sima’s findings in humans, C-peptide could easily be integrated into an insulin-therapy treatment regimen, as C-peptide is already manufactured by drug companies as a byproduct of insulin.

“Given the data, I think it’s realistic to expect that we can directly translate the experimental findings to practical treatment options,” Dr. Sima said. “The concept itself is so simple, it’s almost embarrassing.”

With more than 1,000 medical students, WSU is among the nation’s largest medical schools. Together with its clinical partner the Wayne State University Physician Group, the school is a leader in patient care and medical research in a number of areas, including cancer, genetics, the neurosciences and women and children's health.

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