Diabetes mellitus is a heterogeneous condition with genetic, environmental, behavioral, and pathophysiological components. As a result, precision medicine plays a significant role in its diagnosis and management. The precision diagnosis include the classification of diabetes into its subtypes through the characterization of its genomics, metabolomics, epidemiology, ancestry, geography, clinical features, and diagnostic testing. New distinct phenotypes of diabetes mellitus have been characterized through enhanced clinical data at the population level, and molecular and genetic data at the cellular level. Precise identification of diabetes phenotypes and etiology is crucial for successful disease management, enabling targetes prevention strategies, endotype-specifc therapeutic approaches, and design prevention trials aimed at delaying disease progression and reducing complications.