The effect of ambient ozone on glucose-homoeostasis: A prospective study of non-diabetic older adults in Beijing

Abstract

Objective: To investigate potential effects of short- and medium-term exposure to low levels of ozone (O3) on glucose-homeostasis in non-diabetic older adults. Methods: 166 non-diabetic, older participants in Beijing were deemed eligible to partake in this longitudinal population-based study. Observations were recorded on three separate occasions from November 2016 up until January 2018. Concentrations of outdoor O3 were monitored throughout the study period. Biomarkers indicative of glucose-homeostasis, including fasting blood glucose, insulin, hemoglobin A1c (HbAlc), glycated albumin percentage, Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and Homeostatic Model Assessment of Beta cell function (HOMA-B) were measured at 3 sessions. A linear mixed effects model with random effects was adopted to quantify the effect of O3 across a comprehensive set of glucose-homeostasis markers. Results: short-term O3 exposure positively associated with increased fasting blood glucose, insulin, HOMA-IR and HOMA-B. The effect on glucose occurred at 3-, 5-, 6- and 7-days, although the largest effect manifested on 6-days (5.6%, 95%CI: 1.4, 9.9). Significant associations with both insulin and HOMA-IR were observed on the 3- and 4-days, although the largest effect consistently occured on 4-days with estimations of 90.0% (95%CI: 19.0, 203.4) and 96.5% (95%CI: 14.9, 235.9), respectively. For HOMA-B, positive associations were identified from 3- to 7-days with estimates ranging from 40.0% (95%CI: 2.3, 91.5) to 83.1% (95%CI: 25.3, 167.5). Stratification suggests that women may be more susceptible to short-term O3 exposure with positive associations observed at 1-, 2-, 5-, 6-, and 7-days in both insulin and HOMA-IR. Conclusions: In this study, we found that O3 exposure is at least partially related to the onset of type II diabetes in older adults with no prior history of this condition. O3 therefore acts as a kind of catalyst for metabolic disorders, which is a particular concern when we consider the rise in global concentrations.