A macrophage.

The discovery opens the way for scientists to develop drugs that will treat insulin resistance by targeting the white blood cells and preventing these from moving into fat tissues, where they cause inflammation and the release of cytokines that resist insulin.

Professor Len Harrison from WEHI's Autoimmunity and Transplantation division and other researchers made the discovery while analysing the fat tissue of more than 100 Victorians who had undergone lapband surgery.

The discovery published in the journal Diabetes offers the first proof that macrophages in fat tissues produce cytokines that prevents cells from reacting to the presence of insulin.

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, Harrison said, according to Physorg.com. These complications could be prevented by developing drugs that target certain cytokines released by the macrophages.

Harrison also said macrophages disappear when obese people lose weight. When this happens, the risk of developing insulin resistance and diabetes also disappears, she said.