Heterogeneity in the development of diabetes-related complications: narrative review of the roles of ancestry and geographical determinants.

The risk of developing diabetes-related complications is influenced by a combination of biological factors, clinical factors and social determinants of health that vary across countries and ethnic groups. Available evidence indicates that the incidence of diabetes-related complications is lower in high-income countries in Europe and North America, while other world regions have higher or variable incidence rates. By ethnicity, White individuals tend to have lower risks of most diabetes-related complications with the exception of coronary artery disease. In contrast, Black, East Asian and South Asian individuals have a greater propensity for most complications, notably chronic kidney disease and stroke. In general, ethnic groups that report a higher incidence of diabetes-related complications also exhibit a higher incidence of type 2 diabetes, particularly among younger age groups. Unique clinical phenotypes characterised by more severe insulin resistance and related comorbidities that drive both an earlier age of diabetes onset and manifestation of end-organ damage have been documented in several high-risk ethnic populations, but the genetic and epigenetic contributors have not been fully elucidated. Non-biological determinants, such as disparities in access to preventive care and the adoption of health-promoting behaviour, shaped by a combination of socioeconomic position, education and culture, are equally as significant as biological factors in influencing disease outcomes, if not more so. In this review we summarise the recent literature on the incidence of diabetes-related complications across countries and ethnic groups, highlighting current gaps in research. We provide perspectives on biological, clinical and social attributes as they relate to geographical and ethnic heterogeneity in the development of these complications. Finally, we discuss the effects of international migration on changing disease trajectories to emphasise the impact of environmental changes on the health of individuals with diabetes.