Morbidity and mortality from diabetes and its complications are increasing in populations globally. Different ethnic groups have varying degrees of risk. The concept of ethnicity encompasses numerous factors relevant to health including genetics, socioeconomics and health behaviours. Ethnicity-related discordance in the glycaemic markers used to diagnose diabetes and to identify those at risk of diabetes has been reported. Furthermore, many ethnicity- and country-specific diabetes risk prediction models have been developed. This review provides a thorough discussion of the impact of ethnicity on how diabetes is detected and the evidence for and against ethnicity-specific approaches to diagnosis.