The aim of this study was to evaluate the geographic variation in mortality among individuals with youth-onset insulin-dependent diabetes mellitus (IDDM) across the world. The study was based on the currently available IDDM incidence and mortality data. Mortality data for diabetes in the 0-24 year age group were obtained from the World Health Organization (WHO) statistics. The mortality rates were adjusted for the frequency of occurrence of IDDM and dividing the mortality rates by the IDDM incidence rates which were obtained from the WHO DiaMond project. There was a more than 10-fold geographic variation in mortality between the developed countries and Eastern European populations. The areas with the highest mortality rates were located in Japan, Eastern Europe and Russia. The areas having the best outcome associated with IDDM were Northern Europe, Central Europe, and Canada. An ecological study demonstrated a relationship between the incidence-adjusted mortality (estimated case-fatality) with IDDM incidence itself (Spearman's correlation coefficient = 0.45) as well as infant mortality and life expectancy at birth. These data demonstrated the possibility of an enormous geographic variation in mortality of youth-onset diabetic patients even in developed countries. It is important to note that these excess deaths are potentially preventable. The ecological study also suggested that the mortality differences may be in part related to overall and diabetes related care.