In April 2000, a study from the Air Force was widely reported in newspapers to have shown that agent orange causes diabetes. Only Gina Kolata, a science and health writer for the New York Times, got the story right (NYT, April 20, 2000).
The study authors found that participants with the highest blood levels of dioxin had a 47 percent higher risk for suffering diabetes. Does that tell you that dioxin, an ingredient in Agent Orange, causes diabetes? Of course not. Dioxin is stored in body fat, so people with the most fat stored the most dioxin and thus had the highest blood levels of dioxin.
People who are fat are the ones most likely to suffer diabetes because body fat blocks insulin receptors, which can lead to diabetes. So being fat contributes to diabetes and being fat causes the highest levels of dioxin to be stored in people who are exposed to it. If you are diabetic, see my report on Treatment of Insulin Resistance.