Long-Term Exposure to Ultrafine Particles and Type 2 Diabetes Prevalence

Background/Aim: Recent studies suggested an association between long-term exposure to air pollution and diabetes. However, evidence is still limited, especially for ultrafine particles UFP, diameter <0.1µm) which have a high toxic potential due to their small size but comparably large surface. Methods: We conducted a cross-sectional analysis based on data of the second follow-up (KORA FF4) of the KORA S4 study in Augsburg and two adjacent rural counties, Germany (2013-2014). Long-term exposure to particle number concentration (PNC) as indicator for UFP, ozone, particulate matter with diameters <10µm (PM10), <2.5µm (PM2.5) and 2.5-10µm (PMcoarse), absorbance of PM2.5 (PM2.5abs), nitrogen dioxide and oxides (NO2, NOx) was measured in 2013/14 and individual concentrations at the participants’ residences were estimated by land-use regression. We used logistic regression adjusting for socio-demographic, lifestyle and clinical covariates to assess the association between annual air pollution concentration and prevalence of type 2 diabetes in 2,268 participants. Effect modifications were tested by the inclusion of interaction terms. Results: Our results indicated a positive association for all air pollutants except for ozone. Significant effect estimates were seen for PNC [odds ratio: 1.18 (95%-confidence interval: 1.01;1.39)] per 2,000 particles/cm3 (interquartile range) increase and for PM2.5abs [1.26 (1.01;1.57)] per 3*10-6/m increase. The estimates however decreased after additional adjustment for the percentage of households with low income within a 1km² grid to 1.10 (0.91;1.33) for PNC and 1.10 (0.81;1.49) for PM2.5abs. Effect estimates were higher for men, smokers, residents of the rural counties and physically inactive participants whereas age, low education, obesity and a history of cardiovascular disease did not modify the estimates significantly. Conclusions: As one of the first studies investigating chronic exposure to ultrafine particles and type 2 diabetes our results point towards a positive association highlighting the role of ultrafine particles within the complex mixture of ambient air pollution.