Associations between long-term exposure to ambient particulate air pollution and type 2 diabetes prevalence, blood glucose and glycosylated hemoglobin levels in China

Background: The evidence for an association between particulate air pollution and type 2 diabetes mellitus (T2DM) in developing countries was very scarce.

Objective: To investigate the associations of long-term exposure to fine particulate matter (PM2.5) with T2DM prevalence and with fasting glucose and glycosylated hemoglobin (HbA1c) levels in China.

Methods: This is a cross-sectional study based on a nation-wide baseline survey of 11,847 adults who participated in the China Health and Retirement Longitudinal Study from June 2011 to March 2012. The average residential exposure to PM2.5 for each participant in the same period was estimated using a satellite-based spatial statistical model. We determined the association between PM2.5 and T2DM prevalence by multivariable logistic regression models. We also evaluated the association between PM2.5 and fasting glucose and HbA1c levels using multivariable linear regression models. Stratification analyses were conducted to explore potential effect modification.

Results: We identified 1760 cases of T2DM, corresponding to 14.9% of the study population. The average PM2.5 exposure for all participants was 72.6μg/m(3) during the study period. An interquartile range increase in PM2.5 (41.1μg/m(3)) was significantly associated with increased T2DM prevalence (prevalence ratio, PR=1.14), and elevated levels of fasting glucose (0.26mmol/L) and HbA1c (0.08%). The associations of PM2.5 with T2DM prevalence and with fasting glucose and HbA1c were stronger in several subgroups.

Conclusions: This nationwide cross-sectional study suggested that long-term exposure to PM2.5 might increase the risk of T2DM in China.