Type 1 (T1D) and Type 2 diabetes (T2D) represent a demanding set of biopsychosocial challenges for patients and their families, whether the age of disease onset occurs in childhood, adolescence, or adulthood. Psychological conditions, defined as syndromes, disorders, and diabetes-specific psychological issues affect a larger proportion of individuals with T1D and T2D compared to the general population. In this review, we summarize the prevalence, impact and psychological treatments associated with the primary categories of psychological conditions that affect adults with T1D and T2D: depressive symptoms and syndromes, anxiety disorders, eating behaviors and disorders and serious mental illness. The implications of the literature for psychologists are discussed, and priorities for future research to advance the science of psychological conditions for adults with T1D and T2D are identified. (PsycINFO Database Record