New research presented at the Annual Meeting of the European Association for the Study of Diabetes (EASD) suggests a significant correlation between living in rural environments during the first five years of life and an increased risk of developing type 1 diabetes (T1D). The study, led by Samy Sebraoui and Professor Soffia Gudbjornsdottir from the University of Gothenburg, explores how early environmental factors may affect the onset of this chronic autoimmune condition.
Type 1 diabetes occurs when the immune system attacks insulin-producing beta cells in the pancreas, resulting in little to no insulin production. This can lead to hyperglycemia, a condition characterized by elevated blood sugar levels. T1D is most commonly diagnosed in children and young adults but can manifest at any age. Patients typically require lifelong insulin therapy.
Sweden has the second highest incidence of T1D globally, which has prompted researchers to investigate potential environmental risk factors. Previous studies primarily focused on patient location at the time of diagnosis, with limited attention given to the living conditions at birth. This new research aims to fill that gap by analyzing T1D incidence across various living environments from birth to diagnosis.
Data was collected from the Swedish National Diabetes Register, identifying all patients diagnosed with T1D between 2005 and 2022, aged 0 to 30 years. The study examined residential addresses throughout their lives, using statistical methods to identify significant risk clusters.
The findings revealed that among the 21,774 diagnosed patients, 58% were male, and approximately three-quarters were under the age of 18 at diagnosis. The mean age of diagnosis was 13.6 years, with males diagnosed at an average of 14.1 years and females at 12.9 years. Notably, 24% of the patients had relocated to different municipalities from birth to diagnosis.
High-risk clusters were identified predominantly in rural areas of Sweden. The analysis indicated that the relative risk of developing T1D in these rural regions was between 30% and 80% higher than national averages. In stark contrast, major cities like Stockholm, Gothenburg, and Malmö exhibited significant low-risk clusters, with a risk reduction of 20% to 50%.
The researchers expressed surprise at these findings, stating, “This finding was unexpected and highlights the need for environmental studies to investigate potential risk factors in rural areas, as well as possible protective factors in urban settings.”
In a subsequent analysis focusing solely on the main residential location during the first five years, the study identified 11 high-risk clusters in rural settings, with elevated risks of developing T1D ranging from 20% to 2.7 times higher than national averages. Northern regions exhibited the most significant relative risks. Conversely, 15 low-risk clusters were found in urban areas, where the risk was noted to be 20% to 88% lower than the national average. Middle-sized cities in southern Sweden, such as Växjö (88% lower), Norrköping (64% lower), and Halmstad (61% lower), showed the lowest risks.
The land use and cover analysis revealed distinct differences between high- and low-risk regions. High-risk areas were often characterized by agricultural land or forested regions, while low-risk clusters were predominantly urban or open land. The authors highlighted the clear geographical variation in T1D incidence, stating, “The first five years of life exhibited the strongest association with high- and low-risk clustering.”
The study’s authors hypothesize that environmental exposures in rural areas, particularly during early childhood, may elevate the risk for T1D. They suggest potential avenues for further research, such as the role of viral infections, which are more common in urban environments and may offer some protection against autoimmune diseases like T1D. Conversely, rural living could lead to increased exposure to pesticides and allergens.
Concluding their findings, the researchers noted the unexpected nature of the results, emphasizing the need for detailed investigations into environmental factors that may influence the development of type 1 diabetes. They plan to explore the lifestyle differences between urban and rural areas in future studies, aiming to uncover the underlying causes of this significant health issue.
