One-Year Age Increment and Sex Differences in the Relationship between Long-Term Exposure to PM 2.5 and Fasting Plasma Glucose Levels in Chinese Children and Adolescents Aged 6-17 Years: Exploring an Independent Risk Factor and Precise Intervention Time Clues

Abstract

Background: Previous studies on the association of PM2.5 exposure with fasting plasma glucose levels (FPGLs) are limited to short- and mid- term PM2.5 exposure duration and lack adjustments for key confounders. Systematically exploring the relationship between long-term PM2.5 exposure and FPGLs in Chinese children and adolescents aged 6-17 years is a necessity. Methods: Between September 2013 and December 2013, 16489 participants aged 6-17 years were recruited using a four-staged, stratified, cluster sampling strategy from 7 provinces, autonomous regions and municipalities on the Chinese mainland. A generalized linear mixed model (GLMM) was used to estimate the relationship of annual PM2.5 exposure (2007-2013) with FPGLs stratified by sex and one-year age increments. Sociodemographics, whether living with parents, early-life factors, behaviors, and infection symptoms were gradually adjusted from the crude model to regression model 6; BMI was adjusted in model 7. Findings: The annual concentration of PM2.5 was 56·23 (±12·99) µg/m3. The mean FPGLs of the 8551 boys (4·75 mmol/L±0·52) was significantly higher than that of the 8194 girls (4·63 mmol/L±0·48). In model 6, each 1 I¼g/m3 increase in PM2.5 was associated with point estimates (95% CIs) of FPGLs of 0·0045 (0·0028 to 0·0063) mmol/L (pi¼œ0·0001) and 0·0050 (0·0035 to 0·0065) mmol/L (pi¼œ0·0001) for boys and girls, respectively. FPGLs were significantly positively associated with long-term PM2.5 exposure at 12, 15 and 16 years old in both boys and girls, accompanied by age differences in model 7. The prevalence of impaired fasting plasma glucose (IFPG) decreased by 0·18% in model 6; assessing the negative effects of PM2.5 exposure revealed that 29,226 children and adolescents would have been protected from IFPG in 2013 in China. Interpretation: Long-term PM2.5 exposure may be an independent risk factor for elevated FPGLs. The adverse effect of PM2.5 exposure on FPGLs in children and adolescents could appear after 10 years of cumulative exposure time. Clues regarding the precise intervention time were revealed at approximately 12 and 11 years of age in boys and girls, respectively. There are great public health implications of early prevention strategies to eradicate the negative effects of long-term exposure to PM2.5 on FPGLs. Funding Statement: Public Welfare Industry of Health of the Ministry of Health of China; National Natural Science Foundation of China. Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: The project was approved by the ethics committee of Peking University. All participants and their parents voluntarily signed the informed consent form.