Type 1 diabetes is caused when certain white blood cells, called T cells, go haywire and begin attacking insulin-producing cells in the pancreas. But not all T cells cause harm, said Dr. Pere Santamaria of the University of Calgary in Alberta, whose study appears in the journal Immunity. "Essentially, there is an internal tug-of-war between aggressive T cells that want to cause the disease and weaker T cells that want to stop it from occurring," Santamaria said in a statement. Santamaria's team wanted to find a way to counteract the harmful autoimmune response without compromising general immunity. They developed a so-called nanovaccine -- particles many times smaller than a cell and coated with protein fragments specific to type 1 diabetes. These were bound to molecules that play a critical role in presenting these protein fragments to T cells. When the team gave the vaccine to mice with an early form of type 1 diabetes, they found the vaccine slowed the progression of the disease. And in mice that had full-blown diabetes, the vaccine helped restore normal blood sugar levels.