We have known for several years that Hepatitis C, a common cause of liver cirrhosis and cancer, also makes people three to four times more likely to develop Type 2 diabetes.
In studying the insulin resistance of 29 people with Hepatitis C, Australian researchers have confirmed that they have high insulin resistance, a precursor to diabetes. However, almost all insulin resistance was in muscle, with little or none in the liver, a very surprising finding given that Hepatitis C is a liver disease.
Dr Kerry Lee Milner and Professor Don Chisholm from Sydney's Garvan Institute of Medical Research, in collaboration with Professor Jacob George from the Storr Liver Unit, University of Sydney at Westmead Hospital, have published their study in the prestigious international journal, Gastroenterology, now online.
Insulin, a hormone made by the pancreas, helps the body use glucose for energy. The two most important organs that respond to insulin are the liver and muscle. A healthy liver responds to insulin by not producing glucose, while healthy muscle responds by using glucose. An insulin resistant liver produces unwanted glucose, while insulin resistant muscle cannot absorb it from the bloodstream, leading to high levels of sugar in the blood.
"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," said Professor Chisholm.
"The fifteen people with very high levels of fat in the liver had the same degree of insulin resistance as the fourteen that didn't have fatty livers."
"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."
"Before you get Type 2 diabetes, you must become insulin resistant and your insulin producing cells must also fail to compensate. Insulin resistance alone will not give you diabetes."