Exposure to air pollution increases the risk of developing insulin resistance as a pre-diabetic state of Type-2 diabetes, the study said. "Whether the disease becomes manifest and when this occurs is not only due to lifestyle or genetic factors, but also due to traffic-related air pollution," said Professor Annette Peters from Helmholtz Zentrum Muenchen - German Research Centre for Environmental Health, located in Neuherberg, in Germany. For the study, published in the journal Diabetes, the researchers analysed data of nearly 3,000 participants of the KORA (Cooperative Health Research in the Region Augsburg conducted in Germany between 2006-2008) study who live in the city of Augsburg and two adjacent rural counties.