The reported prevalence of GDM has varied widely among different populations around the world. Much of this variability results from the differences in diagnostic criteria and methods for detection that are used in different centres. Recent data from Australia and the USA confirm earlier findings that the incidence of GDM varies among ethnic and racial groups. It is important to note that within each ethnic group, GDM prevalence has increased over time. For any given maternal age, the frequency of GDM has exhibited a similar increase.

Large population-based studies in the United States that have controlled for maternal age and ethnicity have found a substantial increase in the overall incidence of GDM over the past decade, particularly in populations in rapid transition. The increase in GDM has paralleled the increase in obesity within the population in the reproductive age. The increase in overweight and obesity among adolescents and young adults is of major concern. Further investigation is required to establish if this weight increase is either causal for or a concomitant of GDM.

Figure 1 | Increasing incidence of GDM in Northern California, USA, 1991 - 2000 

Adapted from Ferrara et al, 2004   1