Despite the advancements in medical sciences, some diseases are becoming epidemic worldwide. One such disease is type 2 diabetes mellitus (T2DM), a chronic disorder linked in part to lifestyle. T2DM is associated with an increased frequency of cardiovascular as well as cerebrovascular diseases, causing significant morbidity and mortality among affected patients. According to recent reports, in Asian countries including Korea, the increasing trends are more significant and the estimated average increases are predicted to surpass the worldwide average. In addition, epidemiological investigations have shown that the onset of disease in Asians is earlier. The complications associated with disease, therefore, occur earlier and the predicted lifespan of affected individuals is known to be shorter. Therefore, improved understanding of the pathophysiology of T2DM is needed for improved prevention, early diagnosis, and disease intervention. However, most of the basic knowledge on the etiology and epidemiology of diabetes is based on reports from Western countries. Thus, they do not reflect the different characteristics of Asian ethnicity, lifestyles, and economics. Several metabolic problems are associated with the development of type 2 diabetes mellitus in a complex manner. In particular, with the deterioration of insulin resistance, the aggravation of the insulin secretory function is understood to play a key role in explaining the pathogenesis of T2DM in our population. In particular, the deterioration of insulin secretion may be an indispensable condition that is inevitable for the development of T2DM in individuals. Even if the insulin resistance of individuals were aggravated limitlessly, a normal glucose tolerance of individuals could be maintained if adequate corresponding compensatory insulin secretion occurs. Further characterization of diabetes in our population is necessary through prospective clinical study.