Air pollution and gestational diabetes mellitus: evidence from cohort studies

Abstract

Exposure to different air pollutants has been linked to type 2 diabetes mellitus, but the evidence for the association between air pollutants and gestational diabetes mellitus (GDM) has not been systematically evaluated. We systematically retrieved relevant studies from PubMed, Embase, and the Web of Science, and performed stratified analyses and regression analyses. Thirteen studies were analyzed, comprising 1 547 154 individuals from nine retrospective studies, three prospective studies, and one case–control study. Increased exposure to particulate matter ≤2.5 µm in diameter (PM2.5) was not associated with the increased risk of GDM (adjusted OR 1.03, 95% CI 0.99 to 1.06). However, subgroup analysis showed positive correlation of PM2.5 exposure in the second trimester with an increased risk of GDM (combined OR 1.07, 95% CI 1.00 to 1.13). Among pollutants other than PM2.5, significant association between GDM and nitrogen dioxide (NO2) (OR 1.05, 95% CI 1.01 to 1.10), nitrogen oxide (NOx) (OR 1.03, 95% CI 1.01 to 1.05), and sulfur dioxide (SO2) (OR 1.09, 95% CI 1.03 to 1.15) was noted. There was no significant association between exposure to black carbon or ozone or carbon monoxide or particulate matter ≤10 µm in diameter and GDM. Thus, systematic review of existing evidence demonstrated association of exposure to NO2, NOx, and SO2, and the second trimester exposure of PM2.5 with the increased risk of GDM. Caution may be exercised while deriving conclusions from existing evidence base because of the limited number and the observational nature of studies.

Air Pollution, Residential Greenness and Metabolic Dysfunction during Early Pregnancy in the INfancia y Medio Ambiente (INMA) Cohort

“…Recent meta-analyses on NO 2 and GDM report either null associations [19,22] or marginal (and imprecise) pooled effect estimates [18,20,21]. Prior evidence on associations between PM 2.5 and gestational diabetes during pregnancy is also inconsistent [17][18][19][20][21][22]. We also observed differing results for residential greenness depending on which metabolic outcome was under investigation, as well as on which metric was used.…”

“…In contrast, we found inverse associations for elevated total triglycerides. Recent meta-analyses on NO 2 and GDM report either null associations [19,22] or marginal (and imprecise) pooled effect estimates [18,20,21]. Prior evidence on associations between PM 2.5 and gestational diabetes during pregnancy is also inconsistent [17][18][19][20][21][22].…”

“…Furthermore, some constituents of particulate matter are endocrine disruptors, which may have potentially adverse effects on pregnancy, including metabolic diseases [15]. While the literature supports an association between air pollution and type 2 diabetes [16], six recent meta-analyses reported mixed results for air pollution and GDM [17][18][19][20][21][22]. More recently, investigations have applied land use regression (LUR) models based on data from monitoring networks [23][24][25][26][27].…”

Ambient PM gross β-activity and glucose levels during pregnancy

“…The finding that second trimester is a sensitive window of exposure for higher pregnancy glucose levels aligns with findings from previous studies evaluating the association between PM 2.5 and GDM. In fact, a recent systematic review of cohort studies found that only second-trimester exposure affects glucose homeostasis [ 10 ]. As such, this present study may further support the possibility that the radiometric component of PM could not only impact GDM, but also, more subtly, pregnancy glucose levels that do not meet the clinical threshold for GDM.…”

“…Several air pollutants, specifically nitrogen dioxide, nitrogen oxides, sulfur dioxide, and particulate matter (PM) with an aerodynamic diameter ≤ 2.5 μm (PM 2.5 ), have been previously identified to be associated with an increased risk of GDM [ 10 ]. While PM 2.5 during pre-pregnancy and the first trimester appear to have a null association with GDM, second-trimester exposure to PM 2.5 has been found to be associated with glucose metabolism [ 10 ]. Oxidative stress and inflammation from PM 2.5 are thought to be the primary mechanisms by which this exposure might increase GDM risk [ 11 ].…”