Obesity diabetes link found

By Dr. Ananya Mandal, MDAug 16 2010

Melbourne researchers from the Walter and Eliza Hall Institute have found that inflammatory cells in fat tissue cause the body to become resistant to the effects of insulin – a common precursor to type II diabetes.

This finding will aid in drug development for insulin resistance in diabetes management where the body is unable to use the hormone to convert food into energy. Scientists say immune systems of overweight people reacted against fat tissue as though it were an infection, causing complications including insulin resistance. This, they said could explain the disease's prevalence among Aborigines, who the researchers said could have a very strong immune response to infections.

More than 50 per cent of Australian adults are overweight and there are an estimated 1.2 million people in Australia who suffer from type 2 diabetes. The study involved analysis of fat tissue of more than 100 Victorians who had undergone lap-band surgery for severe or morbid obesity over four years.

Professor Len Harrison and Dr John Wentworth from the institute’s Autoimmunity and Transplantation division were involved in this study. Dr. Wentworth said, “We believe the inflammation in the fat tissue in obesity is driving diabetes…It's a slightly different view of how body weight promotes diabetes and it opens the possibility that we can develop anti-inflammatory treatment for diabetes that may be better than the current therapies available.” Lead researcher Professor Harrison said, “But the pay-off is that when they switch to a Western diet, which is high in fat, it stimulates these immune cells and consequently they get insulin resistance and diabetes.” Professor Harrison said the finding was important to tackle the “raging epidemic” of obesity, which was set to pose major health risks and costs in the future.

“The complications of obesity such as insulin resistance and diabetes, cardiovascular disease associated with hardening of the arteries, and liver problems are the result of inflammation that occurs in the fat tissue,” Professor Harrison explained. “These complications could be prevented by developing drugs that target certain cytokines released by the macrophages. “Encouragingly, our study also showed that when obese people lost weight the macrophages in the fat tissue disappeared, as did the risk of developing insulin resistance and diabetes.”

Their findings, published in the journal Diabetes. The research was supported by the Australian National Health and Medical Research Council, the Victorian Government, Diabetes Australia Research Trust and the Royal Australasian College of Physicians Research and Education Foundation.