Residential greenness exposure and repeatedly measured hyperglycemic markers in women with gestational diabetes mellitus: A birth cohort study in Foshan, China.

OBJECTIVES

To investigate the association between residential greenness exposure and repeatedly measured hemoglobin A1c (HbA1c) levels during pregnancy in women with gestational diabetes mellitus (GDM).

STUDY

DESIGN

This was a cohort study.

METHODS

This study was conducted in Foshan City, Southern China from January 1, 2016 to August 31, 2022. Women with GDM who had two HbA1c measurements during their pregnancy were included in the analysis. Residential greenness was assessed using the satellite-derived Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) in different buffer areas. Multivariable linear regression models were used to investigate the associations between residential greenness exposure and glycemic levels during middle and late pregnancy. Linear mixed-effect models were used to analyze the association between greenness exposure and repeatedly measured glycemic levels.

RESULTS

Among 5,814 pregnant women with GDM, the mean HbA1c levels were 5.04 (±0.54) % and 5.39 (±0.57) % in middle and late pregnancy, respectively. Greenness exposure before and throughout pregnancy was associated with decreased HbA1c levels from middle to late pregnancy. In the adjusted models, each 0.1 increase in NDVI and EVI value was associated with a 0.01 % (95 % confidence interval [CI]: -0.02 %, -0.01 %) to 0.03 % (95 % CI: -0.04 %, -0.01 %) decrease in HbA1c levels during middle and late pregnancy. Similar findings were observed in a longitudinal analysis of the associations between greenness exposure and HbA1c levels.

CONCLUSIONS

Greater residential greenness exposure was associated with lower HbA1c levels from middle to late pregnancy in women with GDM.