Does environment impact type 1 diabetes?

Type 1 diabetes are increasing worldwide. However, scientists and researchers have struggled to identify a direct cause.

Many have questioned if changes in the environment or lifestyle have impacted the condition. A newly released paper published in The Lancet Diabetes & Endocrinology examines whether any environmental exposures can explain why type 1 diabetes is on the rise.

Jill Norris, Professor and chair of epidemiology at the Colorado School of Public Health and lead author of the paper said, “The incidence of type 1 diabetes has increased 3 percent per year over the past three decades. This increase is too rapid to be due to just genetic factors, suggesting that environmental factors may play a role.”

Identifying environmental factors associated with type 1 diabetes that influence its incidence can inform future preventive trials and searches for other environmental risk factors.

About the research

In this paper, researchers reviewed the literature on environmental factors like air pollution, diet, childhood obesity, the duration of breastfeeding, introduction of cow’s milk, infections, and many other factors that showcase an impact on type 1 diabetes.

The researchers then looked at prevalence of an exposure over time while varying its annual increase under simulated scenarios. Using the simulated data, the research showed that if a single factor were to explain the changes in the incidence of type 1 diabetes over the past few decades, it would have to be very strongly associated with the risk of type 1 diabetes.

The results

The simulated scenarios showed that an environmental factor that increased at a constant rate from nearly absent in the population to nearly ubiquitous would have to confer a relative risk of 5 to explain an approximately 3 percent annual increase in the incidence of type 1 diabetes. However, most of the environmental factors reviewed had a relative risk of less than 2.

“While several factors have been associated with type 1 diabetes, none of the associations are of a magnitude that can explain the rapid increase in incidence alone,” Norris said. “Moreover, evidence of the changing prevalence of these same exposures over time is not convincing nor consistent.”

What’s next?

The paper explains that more research is required, and it is possible that multiple factors may simultaneously account for the increase in type 1 diabetes.

The study concludes that the identification of environmental factors influencing type 1 diabetes risk and increased understanding of the etiology at the individual level, regardless of the ability to explain the changing incidence at the population level, is important because of the implications for prevention.

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