But the exact mechanisms of the phenomenon have been unclear.
Three papers, one from Japan, one from Canada and one from the United States, showed that immune system cells known as T cells were deficient in obese mice, pushing the immune system to somehow initiate insulin resistance.
Restoring T cells to more normal levels actually reversed weight gain and improved insulin resistance, even when the mice continued on a high-fat diet.
The fourth study looked at another class of immune cells called mast cells, which are more commonly linked to allergies.
An over-abundance of mast cells contributed to obesity and diabetes in mice, but when mast cells were removed from the system the problem was corrected, explained study senior author Guo-Ping Shi, a biochemist with Brigham and Women's Hospital in Boston.
"We gave mice a high-fat diet for three months and they developed obesity and diabetes," he said. But mice that had been stripped of mast cells did not. "These mice are protected from the disease if they are without these cells," Shi said.
Shi's team also gave wild-type ("normal") mice allergy medicines, which work to "stabilize" mast cells. This also led to improvements in the mice.
"We can use the drugs to manipulate cell activity or prevent disease in this case," Shi said.
Shi said he has signed a contract with a local company to develop a version of the drugs to combat diabetes in humans.
There's more on type 2 diabetes at the American Diabetes Association.
SOURCES: Guo-Ping Shi, D.Sc., biochemist, Brigham and Women's Hospital, Boston; Vivian Fonseca, M.D., professor, internal medicine, Texas A&M Health Science Center College of Medicine, chief, endocrinology, and director, Diabetes
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