The number of people with diabetes worldwide has more than doubled during the past 20 years. One of the most worrying features of this rapid increase is the emergence of type 2 diabetes in children, adolescents, and young adults. Although the role of traditional risk factors for type 2 diabetes (eg, genetic, lifestyle, and behavioural risk factors) has been given attention, recent research has focused on identifying the contributions of epigenetic mechanisms and the effect of the intrauterine environment. Epidemiological data predict an inexorable and unsustainable increase in global health expenditure attributable to diabetes, so disease prevention should be given high priority. An integrated approach is needed to prevent type 2 diabetes, taking into account its many origins and heterogeneity. Thus, research needs to be directed at improved understanding of the potential role of determinants such as the maternal environment and other early life factors, as well as changing trends in global demography, to help shape disease prevention programmes.