Can Green Spaces Save Lives in Type 2 Diabetes?

TOPLINE:

Long-term exposure to fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) increases cause-specific mortality in those with type 2 diabetes (T2D), whereas increased green space exposure is linked to reduced mortality.

METHODOLOGY:

• Epidemiological studies have linked air pollution exposure to increased cause-specific mortality across the general population, including fatality from diabetes and diabetes-related complications.
• Researchers assessed the long-term effects of exposure to air pollution and green spaces among 174,063 participants (mean age, 64.4 years; 52.9% men) newly diagnosed with T2D from a prospective cohort in Shanghai, China, between 2011 and 2013.
• Participants’ residential exposure to air pollutants, including PM_2.5, inhaled PM, and NO₂, was derived from satellite-based exposure models.
• The level of greenery in the vicinity was assessed using the Normalized Difference Vegetation Index (NDVI).
• One-year average exposures to air pollutants and greenness for each participant were computed annually, and cause-specific mortality was assessed using data obtained from the Shanghai data registry.

TAKEAWAY:

• Over a median follow-up period of 7.9 years, equivalent to 1,333,343 person-years, there were 22,205 deaths recorded.
• Long-term exposure to PM_2.5 was associated with an increased risk for mortality across all causes, with each 10 μg/m³ increase in PM_2.5 levels increasing the risk for mortality due to peripheral vascular diseases by 2.70 times and gastrointestinal cancer by 2.42 times.
• The effect of exposure to NO₂ became evident at concentrations exceeding 45 μg/m³, with each 10 μg/m³ increase in NO₂ levels increasing the risk for mortality due to lung cancer and gastrointestinal cancer by 1.20 times and 1.19 times, respectively.
• Conversely, each interquartile range increase in the NDVI was linked to a 6%-24% reduced risk for mortality across various diseases, with the risk for mortality due to peripheral vascular diseases reducing by 24%.
• The reduction in PM_2.5 and NO₂ levels could mediate 23.8% and 26.6% of the mortality risk-associated benefits of the residential green space, respectively.

IN PRACTICE:

“These findings support the need for policymakers, public health experts, and urban planners to develop greener, more sustainable neighborhoods in regions with high air pollution and diabetes prevalence,” the authors wrote.

SOURCE:

The study was led by Chunfeng Wu and Jiangdong Liu, School of Public Health, Key Laboratory of Public Health Safety of the Ministry of Education and NHC Key Laboratory of Health Technology Assessment, Fudan University, Shanghai, China. It was published online in eBioMedicine, which is part of The Lancet Discovery Science.

LIMITATIONS:

Despite using high spatial resolutions for air pollution and the NDVI, exposure misclassification is possible due to the lack of continuous exposure monitoring and potential residential mobility during follow-up. The NDVI is a broad indicator of the level of greenery in the vicinity and does not consider the quality or specific types of green spaces, which could affect health outcomes through varied mechanisms. The relatively short follow-up period may not fully capture the long-term effects of air pollutants and greenery.

DISCLOSURES:

The study was funded by the Sixth Three-Year Action Program of Shanghai Municipality for Strengthening the Construction of Public Health System, the National Key Research and Development Program, and the National Natural Science Foundation of China. The authors declared no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.