Descriptive epidemiology of type 1 diabetes—is it still in?

This edition of ‘Then and now’ discusses the valuable contribution made by Onkamo and colleagues to the field of type 1 diabetes epidemiology in their widely cited paper ‘Worldwide increase in incidence of type I diabetes–the analysis of the data on published incidence trends’, which was published 13 years ago (Diabetologia 1999;42:1395–1403). At the time, this represented the most extensive analysis of global trends in the epidemiology of type 1 diabetes, and covered/included a considerably larger geographical area than previous studies. The data confirmed that there was a worldwide increase in the incidence of childhood diabetes during the second half of the 20th century. Predictions made by the group for the incidence rates in 2010 pointed to large increases, but in retrospect these turned out to be too conservative, particularly among younger children. Whether the increase in incidence among children aged <15 years has started to level off is unknown. Looking to the future, more data on the epidemiology of type 1 diabetes over the whole lifespan are definitely needed. In addition, descriptive epidemiology needs to be complemented with ‘aetiological’ epidemiology generating information on the causes of the incidence and prevalence trends.