Overeating could be linked to insulin resistance

Australia researchers have discovered a chemical process in the body that causes one of the first stages of type 2 diabetes.

 

Scientists at the Garvan Institute of Medical Research in Sydney, led by Dr Kyle Hoehn and Professor David James, found overeating triggers cells to convert oxygen in the air we breathe into free radical molecules called superoxides, which appear to cause insulin resistance.

 

“When we breathe in oxygen it’s used, in combination with the food that we eat, to produce energy”, said Professor David James, Director of Garvan’s Diabetes and Obesity Research Program.

 

“Sometimes when the supply of nutrients is too high (eg. when we overeat) this process may go awry and one electron may be released from oxygen to generate what is called a free radical.”

 

“Free radicals are dangerous because they can cause damage to many of our cellular molecules that are required for every day life”.

 

The superoxides seem to trigger a process that stops cells accepting fresh nutrients and so levels of blood glucose rise too high in the blood, causing complications and eventually type 2 diabetes.

 

The researchers say that the same chemical process occurs with other sources of insulin resistance including pregnancy, lack of exercise and a range of medical conditions.

 

The production of superoxides takes place in a part of the body’s cells called the mitochondria, the area of the cell where most of our energy is produced. This is significant because antioxidant products currently available to treat free radicals may not be able to reach the superoxides and stop the damage.

 

However, research on mice has shown that removing superoxides, or the ability of mitochondria to produce them, using either drugs or gene therapy allows blood glucose levels to return to normal. This raises hopes that this discovery may lead to new therapies in the future that can prevent or treat type 2 diabetes.

 

The next step, according to Professor James, is todevelop a system using an approach that looks at all factors to identify signs that predict the chance a person has of getting a disease.

 

“Most research focuses on one or two molecules but we believe that this is no longer good enough. We now have to develop methods to look at our organs as working machines”, he said.

 

“Just like machines our organs function by the use of thousands of molecules working together. It may be very difficult to predict what is wrong with the body simply by looking at one or two of the components. We need to look at all of them.”

 

Professor James also noted the importance of reducing overeating in society to tackle this concern.

 

“The problem with overeating is a lot like that facing smoking and cancer – everything thinks it won’t happen to them”, he said.

 

“We need to better educate people about how many calories people should eat a day”.

 

“The findings bring us one step closer to this as it seems likely that calorie intake thresholds vary from person to person; so if we can scientifically measure this we are ahead of the game and this is our long term goals”.