Diabetes Health Center

Another Study Suggests Inflammation May Trigger Diabetes

July 17, 2001 -- Type 2 diabetes is fast becoming one of the major public health problems of the 21st century, with an estimated 15 million Americans already affected and new cases being diagnosed daily.

Obesity and a sedentary lifestyle are known risk factors for the disease, but now a new study points to another important risk factor. The immune system and inflammation may be factors causing type 2 diabetes, and this information may lead to new approaches for testing and treating this disease.

There are two main types of diabetes. Type 1 is when the body loses the cells that make insulin, a hormone that helps regulate the metabolism, putting sugar and fat into storage. Type 2, the focus of the current research, is when the body doesn't respond appropriately to insulin.

In the new finding, published in this week's issue of the Journal of the American Medical Association, Harvard researchers report that when they studied a large group of healthy women for several years they discovered that women who had high levels of immune system substances called C-reactive protein or interleukin-6, or both, in their blood were more likely to develop type 2 diabetes than women who had normal levels of the two factors.

Both C-reactive protein, called CRP, and interleukin-6, or IL-6, are considered indicators for inflammation, says researcher Paul M. Ridker, MD, PhD.

For example, Ridker says that after accounting for known diabetes risk factors like obesity, high blood pressure, high cholesterol, and family history of diabetes, women who had the highest levels of IL-6 were more than twice as likely to develop diabetes than were women who had the lowest levels of IL-6. And for CRP the association was even stronger: Women with the highest concentrations of CRP in their blood were four times as likely to develop diabetes.

Ridker's data come from an ongoing study called the Women's Health Study, which has enrolled nearly 28,000 women since 1992. All women had blood tests when they entered the study. Over a four-year period he identified 188 women who developed diabetes and compared them with 362 women who were the same age and who had the same fasting blood sugar levels as the other women when the study started but did not develop diabetes.

Still, Ridker says it is too soon to recommend using CRP testing to gauge the risk for diabetes.

Om Ganda, MD, of the Joslin Diabetes Center and Harvard Medical School, both in Boston, tells WebMD that Ridker's new study is "one of a number of recent studies that have indicated that low-grade chronic inflammation might underlie type 2 diabetes." But Ganda says that there are still several unanswered questions.

"There is a very small number of diabetic cases in this study, just 188 women," says Ganda. He says it is difficult to make assumptions based on so few cases.