IOM Admits Possible Link Between Agent Orange and Type 2 Diabetes

Medically Reviewed by Gary D. Vogin, MD
From the WebMD Archives

Oct. 13, 2000 (Washington, D.C.) -- Soldiers exposed to Agent Orange during the Vietnam War may have twice the risk of developing diabetes than those who avoided the plant-killing chemical. Still, the connection between exposure to the herbicide and development of the illness is tentative, according to a new report from the Institute of Medicine (IOM).

The IOM report, released Wednesday, says there is now "limited or suggestive" evidence of a link to type 2 diabetes, formerly known as "adult-onset diabetes." Previous reports had called the connection "inadequate or insufficient."

"There are potential hazards in all of the chemicals that we use in the environment," study co-author Noel Rose, MD, PhD, tells WebMD. "Sometimes, the effects don't appear until years later, and often the individual risks are very small."

What pushed the evidence in favor of a possible diabetes risk was the release of two new epidemiological studies, says Rose, professor of molecular microbiology and immunology at Johns Hopkins University's School of Hygiene and Public Health in Baltimore. The analyses focused on exposure to herbicides, like Agent Orange, which contain dioxin, a potentially toxic chemical.

"Although some of the risk estimates in the studies examined by the committee are not statistically significant ... the accumulation of positive evidence is suggestive," according to the 66-page report, "Veterans and Agent Orange: Herbicide/Dioxin and Type 2 Diabetes."

Beginning in 1962, the U.S. was involved in massive herbicide-spraying operations in Vietnam to eliminate some of the jungle hiding places for enemy soldiers. However, in 1969, when evidence showed that Agent Orange caused birth defects in lab animals, the military decided to quit using the compound.

Dioxin can alter the ways fat behaves in the body, which in turn affects insulin's impact on blood sugar. The chemical also is considered a risk factor for several different types of cancers.

Still, the IOM was limited in its conclusions. Because it's not clear how many veterans were exposed to Agent Orange or in what dose, the committee depended heavily on studies of troops who worked with herbicides.

Rose says he was touched by personal testimony from the vets.

"Your heart goes out to these people," he says. "But as a scientist you have to say ... we're just devastated that you're ill, but we cannot say for certain that your illness was caused by this, that, or the other thing," he says.

The risk of contracting diabetes from dioxin is extremely small, particularly when compared with obesity, age, or smoking, Rose says.

The IOM report did not address the issue of compensation for Vietnam veterans who have gone on to develop diabetes, but the new report is expected to energize the efforts of veteran advocacy groups seeking such payments.

The IOM is a part of the National Academy of Sciences and prepared the Agent Orange report for the U.S. Department of Veterans Affairs. However, this document isn't necessarily the final word. Under congressional mandate, another committee is being formed to review any new information, and that report should be available at a later date.