Researchers probe Hep C-diabetes link

Australian scientists looked for the reason why people with Hepatitis C often go on to develop diabetes, and they made an unexpected discovery.

The heightened risk of type 2 diabetes was thought to be linked to fat build-up in the liver caused by their Hep C, but tests on people with the blood-borne virus found something else was awry.

The Garvan Institute of Medical Research study confirmed the 29 study participants all had "high insulin resistance" - a precursor to diabetes - but the problem was traced to their muscle and not their livers.

Professor Don Chisholm said this result was "contrary to all expectations".

"... not only did we find no significant insulin resistance in the liver of the patients in the study, half of them suffered from a strain of Hepatitis C that causes about three times the normal level of fat to accumulate in the liver," Prof Chisholm said.

"A number of important investigators around the world have been arguing that fat in the liver is an extremely important determinant of insulin resistance, perhaps the most important.

"At least in this context, we've shown that not to be the case."

Hepatitis C is a liver disease and one of its most common strains - Genotype 3 - is known to cause significant fat deposits in the liver.

Study participants with this strain were shown to have the same level of insulin resistance as those with no liver fat accumulation.

The two most important organs that respond to insulin in the body are the liver and muscle, Prof Chisholm explained.

An insulin-resistant liver produced unwanted glucose while insulin-resistant muscle could not absorb it from the bloodstream, leading to high levels of sugar in the blood.

"More work now needs to be done into why Hepatitis C causes insulin resistance in muscle," Prof Chisholm said.

"That will give us better insight into the behaviour of the disease."

Hepatitis C is transmitted in Australia mainly by drug users sharing needles but also by non-sterile tattooing or body piercing and, unlike Hepatitis A and B, there is no vaccine.

Around 212,000 Australians suffer from chronic Hepatitis C and there are roughly 10,000 new infections each year.

Prof Chisholm conducted the research along with Dr Kerry Lee Milner also from the Garvan Institute, in collaboration with Professor Jacob George from the Storr Liver Unit at the University of Sydney and Westmead Hospital.

Their work is published in the journal Gastroenterology.