For decades, scientists have known that in type 1 diabetes the body's immune system malfunctions and destroys the insulin-producing cells in the pancreas.
Insulin is the hormone that plays a key role in moving glucose, or sugar, from the bloodstream into the body's tissues where it's needed for energy.
Type 2 diabetes, on the other hand, has never been considered an autoimmune disorder. People with this condition produce insulin but they don't use it very efficiently - although scientists don't know why.
A new study by researchers at Stanford University and the University of Toronto, however, suggests that type 2 diabetes may involve immune-system abnormalities after all.
In a series of laboratory experiments, the researchers found they could cause a mouse to develop this form of diabetes by manipulating its immune system.
The researchers also found that blood samples of people with type 2 diabetes contained antibodies against some of their own proteins. In other words, their immune systems have turned on them.
"This data is highly suggestive that there is an autoimmune component in type 2 diabetes," said Daniel Winer, one of the study's lead authors, along with his twin brother, Shawn Winer, both at the University of Toronto.
If further research confirms these findings, published in the journal Nature Medicine, it could lead to new type 2 diabetes treatments that focus on the immune system.