Association of temporal distribution of fine particulate matter with glucose homeostasis during pregnancy in women of Chiayi City, Taiwan

Background: To investigate the effects of fine particulate matter (PM2.5) on the indicators of glucose homeostasis during pregnancy. Methods: A total of 3589 non-diabetic pregnant women who underwent a 3h 100-g oral glucose tolerance test (OGTT) were enrolled from a tertiary teaching hospital in Chiayi City, Taiwan between 2006 and 2014. Fasting, 1-h, 2-h, and 3-h glucose levels after an OGTT were used as indicators of glucose homeostasis. PM2.5 and other air pollution data were obtained from one fixed-site monitoring station (Chiayi City station) operated by Taiwan Environmental Protection Administration (EPA). We used mixed models for indicators of glucose homeostasis to estimate the effects of PM2.5. The models were adjusted for individual-specific effects (nulliparous status, age, body mass index, season, and year) and the moving averages of temperature and relative humidity in the corresponding study period. Results: There were significant relationships between PM2.5 and the glucose homeostasis indicators, including fasting, 1-h, 2-h, and 3-h glucose levels in the single-pollutant covariate-adjusted model. The pre-screening 1 month to 1-year moving averages of IQR increases in PM2.5 were significantly associated with elevated fasting OGTT glucose levels (1.32-5.87 mg/dL). The two-pollutant covariate-adjusted models had similar results. Conclusions: We found positive associations between PM2.5 and OGTT glucose levels during pregnancy. The association was especially pronounced for the fasting and 1-h glucose levels. PM2.5 exposure in the second trimester may enhance this effect. Exposure to PM2.5 was associated with glucose homeostasis during pregnancy.