Non-insulin-dependent diabetes mellitus (NIDDM, type II diabetes) is present in nearly all of the countries of the world, and represents a significant disease burden in most developed countries. Type II diabetes is fairly common among Caucasoid populations in the United States and Europe and, more importantly, among Native Americans, Pacific Island populations, persons of Asian Indian origin, Hispanics and African Americans. Our current understanding is that type II diabetes probably results from an interaction of genetic and environmental factors. While a genetic link is most likely a precursor to type II diabetes, a number of lifestyle behaviours, including obesity, lack of physical activity, and diet, also influence the development of the disease. Lifestyle changes and westernisation that accompany economic development in developing countries have been followed in the past by substantial increases in the prevalence of type II diabetes. Thus, further increases in type II diabetes might be expected in the Third World as the economic advancement of these countries continues.