Air pollution exposures and blood pressure variation in type-2 diabetes mellitus patients: A retrospective cohort study in China

Air pollution exposure has been associated with hypertension, but limited studies have examined the associations in diabetic patients. We aimed to examine the associations of exposure to air pollution with blood pressure in diabetic patients. We identified patients who were previously diagnosed as type-2 diabetes mellitus from hospital records from January 2013 to May 2017. We used generalized linear models to estimate adverse effects of air pollution on systolic/diastolic blood pressure in diabetic patients. A total of 40,125 patients were enrolled in this study. An IQR increase in PM2.5, PM10, NO2, SO2, and O-3 exposure was associated with an increased risk of higher systolic blood pressure level (beta = 0.628 for PM2.5, beta = 0.758 for PM10, beta = 0.766 for NO2, beta = 0.516 for SO2, beta = 0.482 for O-3, all P value < 0.05). Significant associations were observed for some air pollutants and SBP among patients with fasting blood glucose (FBG) >= 7.0 mmol/L, normal weight, and younger age. Little evidence was available for the associations between particulate matter (PM) or O-3 exposure and diastolic blood pressure in present study. In our study, diabetic patients were at increased risk of higher blood pressure when exposed to higher residential PM, NO2 and SO2. Individuals with lower BMI, younger age, and FBG >= 7.0 mmol/L were more susceptible to the adverse effects of ambient air pollution.