In general, the risk factors for type 2 diabetes are pretty clear: A lack of exercise, a poor diet, genes, and ethnicity are the most serious determinants of the disease. But now that more than 29 million Americans have diabetes and 86 million more are prediabetic, researchers are also focusing on other factors that might increase a person’s risk of developing diabetes.
Some of the other culprits thought to be contributing to the diabetes epidemic are chemicals found in the environment and in products we use daily. Certain chemicals may directly increase the risk of the disease, while others may contribute to obesity, a serious risk factor in the development of type 2 diabetes. At this point, research on whether exposure to chemicals can lead to any or all types of diabetes is still in the very preliminary stages, and there’s a lack of randomized controlled studies — the gold standard for medical research — indicating that the two are directly linked. Here’s what we know now.
The Relationship Between Chemicals and Diabetes
“There is an association between some chemicals in the environment and diabetes,” says Kristina Thayer, PhD, director of the Integrated Risk Information System (IRIS) division of the Environmental Protection Agency (EPA) in Research Triangle Park, North Carolina. “What we don’t know is whether it’s causal.” That means that while a number of studies might link a higher level of certain chemicals to a greater likelihood of developing diabetes, it’s not yet clear whether that chemical exposure preceded the diabetes. More research is needed to better establish a potential causal relationship between the two.
Phthalates and BPA
As far as specific chemical culprits, phthalates and bisphenol A (BPA) — common chemicals found in soaps, nail polishes, hair sprays, perfumes, and moisturizers — are implicated. In a study published in July 2012 in the journal Environmental Health Perspectives, researchers found that women with the highest levels of phthalates in their urine had a 70 percent higher risk of diabetes than women with the lowest levels of phthalates in their bodies.
A study published in June 2014 in the journal Environmental Health Perspectives found that phthalate exposure may be associated with a risk of Type 2 diabetes among middle-aged (but not older) women, possibly because premenopausal women may be more susceptible to endocrine disruptors due to higher levels of estrogen.
Arsenic, PCBs, and Dioxins
Another potential chemical culprit of diabetes is arsenic. Areas of Bangladesh and Taiwan have well-documented high levels of arsenic in drinking water. Scientists in those areas have found a strong association between diabetes and people who drink the water, Dr. Thayer says. In the United States, the EPA regulates chemicals like arsenic, so Americans don’t have nearly the level of exposure as people in those other areas. As levels of arsenic decrease to the low-to-moderate range, researchers have found that literature linking its exposure with diabetes becomes less consistent.
Polychlorinated biphenyls (PCBs) and dioxins are among the other chemicals examined and found to have at least some association with diabetes. But determining whether diabetes and these chemicals have a causal relationship is tricky. “A lot of these chemicals are very persistent because they stay in fat — that’s where they’re stored in the body,” Thayer says. “If you have someone who’s overweight or obese, which is an independent risk factor for diabetes, that person is probably going to have higher levels of these chemicals in their fat. It’s hard to disentangle the effect of the chemical versus the health condition of being overweight or obese.” Separately, PCBs, which were banned by the EPA in 1979 but still exist in the environment, have been linked to obesity in adults.
What to Know About Your Risk
Much more research needs to be done to establish how these and other chemicals affect our bodies — and our diabetes risk — Thayer says.
“Diabetes could be caused by a number of factors — probably a combination of factors — and it’s possible a chemical in the environment might be an added risk factor,” she explains. “The best way consumers can act on it now is to work on healthy behaviors that are under their control, such as managing what they eat, how much they eat, and making sure to exercise.”