Particulate Air Pollution and Fasting Blood Glucose in Nondiabetic Individuals: Associations and Epigenetic Mediation in the Normative Aging Study, 2000–2011
Background: Among nondiabetic individuals, higher fasting blood glucose (FBG) independently predicts diabetes risk, cardiovascular disease, and dementia. Ambient PM2.5 (particulate matter with aerodynamic diameter ≤ 2.5 μm) is an emerging determinant of glucose dysregulation. PM2.5 effects and mechanisms are understudied among nondiabetic individuals.
Objectives: Our goals were to investigate whether PM2.5 is associated with an increase in FBG and to explore potential mediating roles of epigenetic gene regulation.
Methods: In 551 nondiabetic participants in the Normative Aging Study, we measured FBG, and DNA methylation of four inflammatory genes (IFN-γ, IL-6, ICAM-1, and TLR-2), up to four times between 2000 and 2011 (median = 2). We estimated short- and medium-term (1-, 7-, and 28-day preceding each clinical visit) ambient PM2.5 at each participant’s address using a validated hybrid land-use regression satellite-based model. We fitted covariate-adjusted regression models accounting for repeated measures.
Results: Mean FBG was 99.8 mg/dL (SD = 10.7), 18% of the participants had impaired fasting glucose (IFG; i.e., 100–125 mg/dL FBG) at first visit. Interquartile increases in 1-, 7-, and 28-day PM2.5 were associated with 0.57 mg/dL (95% CI: 0.02, 1.11, p = 0.04), 1.02 mg/dL (95% CI: 0.41, 1.63, p = 0.001), and 0.89 mg/dL (95% CI: 0.32, 1.47, p = 0.003) higher FBG, respectively. The same PM2.5 metrics were associated with 13% (95% CI: –3%, 33%, p = 0.12), 27% (95% CI: 6%, 52%, p = 0.01) and 32% (95% CI: 10%, 58%, p = 0.003) higher odds of IFG, respectively. PM2.5 was negatively correlated with ICAM-1 methylation (p = 0.01), but not with other genes. Mediation analysis estimated that ICAM-1 methylation mediated 9% of the association of 28-day PM2.5 with FBG.
Conclusions: Among nondiabetics, short- and medium-term PM2.5 were associated with higher FBG. Mediation analysis indicated that part of this association was mediated by ICAM-1 promoter methylation.
1Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA; 2Department of Statistics, Harvard University, Cambridge, Massachusetts, USA; 3Department of Geography and Environmental Development, Ben-Gurion University of the Negev, Beersheba, Israel; 4Human Nutrition Research Center, Institute of Cellular Medicine, Newcastle University, Newcastle, United Kingdom; 5Molecular Epidemiology and Environmental Epigenetics Laboratory, Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy; 6VA Normative Aging Study, Veterans Affairs Boston Healthcare System, Boston, Massachusetts, USA; 7Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA; 8Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA; 9Channing Laboratory, Harvard Medical School, Boston, Massachusetts, USA
Recommended Citation:
Cheng Peng,1 Marie-Abele C. Bind,2 Elena Colicino,et al. Particulate Air Pollution and Fasting Blood Glucose in Nondiabetic Individuals: Associations and Epigenetic Mediation in the Normative Aging Study, 2000–2011[J]. Environmental Health Perspectives,2016-01-01,Volume 124(Issue 11):1715