Inflammation May Play Role in Type 2 Diabetes

NEW YORK (Reuters Health) - Elevated blood levels of two inflammatory substances seem to be independent risk factors for type 2 (adult-onset) diabetes, researchers report.

According to study findings published in the July 18th issue of The Journal of the American Medical Association, middle-aged women with higher levels of interleukin 6 (IL-6) and C-reactive protein (CRP) were significantly more likely to develop type 2 diabetes over a 4-year period than women with lower levels were.

IL-6 and CRP are inflammatory proteins that are released in response to infection and injury. However, chronic elevations in these substances may raise the risk of heart disease. Also, these proteins may be associated with high blood sugar levels and resistance to insulin--factors that often precede the onset of diabetes.

"We suspect there is a 'common soil' which both cardiovascular disease and diabetes share, and that this common underlying cause may be inflammation,'' Dr. Paul M. Ridker, the study's senior author, told Reuters Health.

Ridker, from Brigham and Women's Hospital in Boston, Massachusetts, and his associates studied data from more than 27,000 women over 45 years of age who were free of diabetes, heart disease and cancer when they enrolled in the Women's Health Study. Over 4 years, 188 women developed diabetes, the report indicates.

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The investigators found that those with the highest level of IL-6 were more than twice as likely to develop diabetes as those with the lowest level, regardless of obesity, family history of the disease, smoking, alcohol and exercise habits and use of hormone replacement therapy. Similarly, those with the highest level of CRP were more than four times more likely to be diagnosed with diabetes than those with the lowest level.

Overall, the risk of future diabetes was greatest among women with the highest levels of both proteins, the researchers report.

It is too soon to screen patients for these proteins to measure diabetes risk, Ridker believes. "The primary impact of these data should be to stimulate future research into inflammatory mechanisms of diabetes,'' he said.

Type 2 diabetes affects an estimated 15 million Americans. The disease, which occurs when the body can no longer respond to insulin, the body's key blood sugar-regulating hormone, can raise the risk of heart disease, kidney failure and nerve damage if blood glucose (sugar) is not controlled.

Source: Reuters Health / The Journal of the American Medical Association 2001;286:327-334.