Do Immune System Ills Help Drive Type 2 Diabetes?

New research suggests that the development of insulin resistance and type 2 diabetes may be linked to an immune system reaction gone awry. "The main point of this study is trying to shift the emphasis in thinking of type 2 diabetes as a purely metabolic disease, and instead emphasize the role of the immune system in type 2," said study co-author Dr. Daniel Winer, an endocrine pathologist at Toronto General Hospital in Canada. When the research began, Winer was a postdoctoral fellow at Stanford University in California. The researchers have identified immune system antibodies in people who are obese and insulin-resistant that aren't present in people who are obese without insulin resistance. They also tested a drug that modifies the immune system in mice fed a fatty diet, and found that the medication could help maintain normal blood sugar levels.

The findings were published online April 17 in the journal Nature Medicine. Funding for the study was provided by the U.S. National Institutes of Health. Nearly 26 million Americans have diabetes, according to the U.S. Centers for Disease Control and Prevention. Between 90 percent and 95 percent of these cases are type 2 diabetes, where the body doesn't use insulin efficiently, so the pancreas must make increasing amounts of insulin. Eventually, the pancreas stops making enough insulin to meet the increased demand. The less common form of the disease, type 1 diabetes, occurs when the immune system mistakenly destroys the insulin-producing beta cells in the pancreas. This type of diabetes is considered an autoimmune disease, and isn't linked to how much a person weighs.

Although the causes of type 2 haven't been clear, it's known that the disease runs in families, suggesting a genetic component. Also, while type 2 is strongly linked to increased weight, not everyone who is overweight gets type 2 diabetes. And, that's what got the researchers searching for another factor. Winer explained that excess weight has been linked to inflammation, which can cause the immune system to react. As visceral fat (abdominal fat) expands, it eventually runs out of room, explained Winer. At that point, the fat cells may become stressed and inflamed, and eventually the cells die. When that happens, immune system cells known as macrophages come to sweep up the mess.