Surprising findings about Hepatitis C and insulin resistance
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.'
'In our study, we gave intravenous glucose, a specific stimulus to
insulin secretion, and showed that insulin secretion was not impaired in
Hepatitis C patients compared to our control group.'
'This finding tells us that people with Hepatitis C who develop
diabetes probably have susceptible insulin-producing cells, and would
probably get it anyway - but much later in life. The extra insulin
resistance caused by Hepatitis C apparently brings on diabetes at 35 or
40, instead of 65 or 70.'
'More work now needs to be done into why Hepatitis C causes insulin
resistance in muscle. That will give us better insight into the
behaviour of the disease.'
'At this stage, it is helpful for people with Hepatitis C to
understand insulin resistance and what it can mean for them. If they
have relatives with Type 2 diabetes, they will be genetically prone to
developing it themselves and so would be advised to manage their diets
very carefully and take plenty of exercise - to slow onset.'
Source: Research
Australia
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