The association of exposure to air pollution with changes in plasma glucose indices, and incidence of diabetes and prediabetes: A prospective cohort of first-degree relatives of patients with type 2 diabetes

Background: Increasing incidence rates of diabetes related to air pollution have been reported in high-income countries. However, few studies evaluated air pollution effect on plasma glucose indices, in addition to diabetes and prediabetes incidence in developing countries. This study investigated the association between exposure to common air pollutants and the changes plasma glucose indices over time. The incidence of type 2 diabetes (T2D) and prediabetes in future were also examined in association with exposure to air pollution. Materials and Methods: A total of 3828 first-degree relatives of patients with T2D who were prediabetes or had normal glucose tolerance (NGT) were enrolled in this study. Cox regression was used to assess the relationships between particulate matter (PM2.5 and PM10), nitrogen monoxide (NO), nitrogen dioxide, nitric oxides, sulfur dioxide (SO2), and ozone exposure and the incidence of T2D and prediabetes. We also applied a linear mixed model to assess the association between exposure to these air pollutants and changes in plasma glucose indices over time. Results: Air pollutants showed a significant positive association with changes in fasting plasma glucose (FPG), glycosylated hemoglobin (HbA1c), and 2 h oral glucose tolerance (OGTT) in participants with NGT and prediabetes. The maximum increase in plasma glucose indices was associated with NO concentration. Our study also showed exposure to all air pollutants except SO2 was significantly associated with an increased risk of developing T2D and prediabetes (Hazard ratio > 1, P < 0.001). Conclusion: According to our results, exposure to air pollution increases the risk of T2D and prediabetes incidence in our population. The exposure to air pollutants was also associated with increasing trend in FPG, HbA1c, and OGTT levels in both groups of NGT and prediabetic participants.