The global prevalence of diabetes and associated metabolic diseases has increased dramatically in recent decades. In Korea, the prevalence of diabetes is 12.4%, or an estimated 4.01 million people. The main pathogenesis of type 2 diabetes involves b-cell dysfunction in the pancreas and peripheral insulin resistance. Factors contributing to the development of type 2 diabetes include old age, obesity, lack of physical activity, a family history of diabetes and a genetic predisposition. However, these traditional risk factors alone cannot explain the rapidly increasing prevalence of diabetes worldwide. Recently, much research has examined factors beyond these conventional risk factors, including environmental chemicals, nutrients such as vitamin D and trace elements, and the intestinal microbiome. With uncontrolled industrialization, environmental pollutants have contaminated the air, water and soil. Consequently, people have been exposed to environmental chemicals unknowingly, continually, and chronically through inhalation and ingestion over the past several decades. Sometimes, chemical plant explosions or chemical weapons cause massive, acute exposure to environmental chemicals in specific regions. With the explosive increase in the social burden of diabetes, we must focus on the roles of traditional risk factors in the development of type 2 diabetes, as well as those of emerging environmental chemicals that contribute to the pathogenesis of type 2 diabetes.