Association between Long Term Exposure to Air Pollution, Impaired Fasting Glucose, Impaired Glucose Tolerance and Prevalence of Diabetes

Air pollution exposure have been shown to adversely impact health through a number of biological pathways, and is also associated with glucose metabolism. There are few studies that evaluated the associations between air pollution and fasting blood sugar and HbA1C levels. But no such study occurred in Indian population. Hence to address this knowledge gap, we investigated the associations between air borne fine particulate matter (PM10, PM2.5), nitrogen di-oxide and glucose metabolism in a tertiary care center in north western rajasthan.

Material: We performed cross-sectional analysis in 3457 participants between 30 to 70 years of age group from five different urban and rural areas of Bikaner district. Air pollution concentration of multiple air pollutants (PM10, PM2.5andNitogen dioxide) were estimated by ambient air quality standard method by respiratory dust sampler. Diabetes was defined based on self reported diagnosis, medication prescription, oral glucose tolerance test and HbA1C. We adjusted for potential confounders including socio-economic status, smoking habits, alcohol consumtion, physical activity and Body Mass Index (BMI) by using logistic regression method.

Observation: After adjustment for potential confounders, air pollutants PM10, NO2, except PM2.5 were associated with diabetes prevalence. The prevalence of diabetes was 8.93% and the mean HbA1C was 8.67±1.16, where as the concentration of PM10 was 156.12 mcg/m3, NO2 was 5.43 mcg/m3 and PM2.5 was 25.36 mcg/m3. The prevalence of IFG, IGT and diabetes increases with increased concentration of air pollutants. By applying Pearson's co-relation for air pollutants the 'r' value of PM10was 0.163, p value < 0.001, for PM2.5 'r' value was 0.001 and p value 0.965, for NO2 'r' value was 0.149 and p value was 0.001 respectively. By applying step wise logistic regression analysis, air pollutants PM10 (Odd Ratio 0.002, 95% CI 0.002;0.003) and by adding duration of exposure to air pollutants (Odd ratio 0.003,95%CI 0.001,0.005) by adding PM2.5 air pollutant (odd ratio 0.028,95%CI -0.042,-0.015) and by adding NO2 (odd ratio 0.140,95% CI 0.104,0.175).

Conclusion: long term air pollution exposure was associated with impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and prevalence of diabetes mellitus (DM). This study can be used as a good evidence that air pollution is an important and manageable risk factor for diabetes hence awareness about air pollution in the society and at government level is much needed.