In a double-blind study, participants were given either a placebo or BPA at the US EPA’s safe dose (50 μg/kg body weight) for 4 days to evaluate its impact on insulin sensitivity.

The study included forty healthy, non-active adults (22 females, 18 males) who first completed a 2-day low-BPA diet. During this period, researchers measured urine and blood samples, as well as peripheral insulin sensitivity, using a 120-minute euglycemic hyperinsulinemic clamp.

Participants were then randomly assigned to follow a 4-day diet with either oral BPA (50 μg/kg) or a placebo, without knowing which one they received.

The outcomes were analyzed using repeated measures ANOVA, adjusting for sex, BMI, physical activity, and ethnicity.

The study indicates that bisphenol A (BPA) found in food packaging may directly affect diabetes risk in adults, influencing public health guidelines and policies.

“Given that diabetes is a leading cause of death in the US, it is crucial to understand even the smallest factors that contribute to the disease,” Hagobian said in a news release.

The findings revealed that BPA exposure reduced peripheral insulin sensitivity after four days.

There was no significant change in body weight or fasting blood glucose levels between the placebo and BPA groups over the four days. However, urine BPA levels were significantly higher in those who received BPA.

Importantly, peripheral insulin sensitivity significantly decreased in the BPA group while it remained stable in the placebo group.

As this research continues, two follow-up studies are necessary to thoroughly understand the results.

The first should investigate whether a lower dose of bisphenol A over several weeks or months increases the risk of diabetes. The second should examine whether aerobic exercise, known for significantly reducing diabetes risk, can counteract the negative effects of bisphenol A exposure.

Catherine Rall, a registered dietitian nutritionist with Happy V, not involved in this research, told Medical News Today that “BPA is known to be an endocrine disruptor, and this is going to have effects on insulin sensitivity.”

The study also used a double-blind approach, which supports the reliability of the findings, but the sample size and duration were quite small; they studied 40 participants over the course of several days, while type 2 diabetes is a chronic condition that develops over months and even years. So, there’s more work to be done.

— Catherine Rall, registered dietitian nutritionist

Kubanych Takyrbashev, MD, health and wellness advisor at NAO, also not involved in the research, said, “as a physician reflecting on the research linking Bisphenol A (BPA) exposure to increased risk of type 2 diabetes, I find the implications for patients and the public to be multifaceted and often overlooked in mainstream discussions.”

“BPA, a pervasive endocrine-disrupting chemical found in everyday products, has been shown to disrupt hormone function, potentially leading to insulin resistance—a precursor to type 2 diabetes,” he said.

Takyrbashev added that “beyond the common advice to reduce exposure by avoiding plastics and canned foods, several other implications deserve attention.”

He noted that vulnerable populations, such as pregnant people and children, are particularly at risk due to their developing or sensitive hormonal systems. Indeed, experts believe that minimizing BPA exposure during critical developmental stages is crucial to mitigate long-term health risks.

Furthermore, BPA is just one of many endocrine disruptors people encounter daily.

The cumulative impact of exposure to multiple chemicals, known as the “chemical cocktail effect,” could potentially amplify health risks, including diabetes and other metabolic disorders.

In addition to these health concerns, environmental justice issues come into play, Takyrbashev explained.

Low-income communities and minority groups often face higher exposure to environmental toxins like BPA due to socioeconomic factors and living conditions. Takyrbashev noted that advocating for policies that reduce disparities in exposure is essential to protect these vulnerable populations.

“Emerging research suggests that BPA exposure can influence gene expression through epigenetic mechanisms, potentially predisposing individuals to metabolic diseases across generations. Understanding these effects is crucial for shaping preventive strategies and policies.”

— Kubanych Takyrbashev, MD, physician

In conclusion, Rall added: “This is more evidence of what we’ve already suspected–that BPAs are probably somewhat harmful.”

“I doubt this study will be enough to get them off the market completely, but it may help to generate more attention for this issue,” Rall said.