To examine the association of diabetes stigma with psychological, behavioral, and HbA1c outcomes and to investigate moderation effects of self-esteem, self-efficacy, and/or social support.The national Second Diabetes MILES-Australia (MILES-2) survey included adults with type 1 diabetes (n = 959, 41% of whom were male, with mean ± SD age 44 ± 15 years), insulin-treated type 2 diabetes (n = 487, 60% male, age 61 ± 9 years), and non-insulin-treated type 2 diabetes (n = 642, 55% male, age 61 ± 10 years). (Un)adjusted linear regression analyses tested the association between diabetes stigma (Diabetes Stigma Assessment Scale [DSAS]) and psychological outcomes (depressive symptoms [eight-item version of the Patient Health Questionnaire (PHQ-8)], anxiety symptoms [Generalized Anxiety Disorder 7-item (GAD-7) questionnaire], and diabetes-specific distress [20-item Problem Areas In Diabetes (PAID) scale]), behavioral outcomes (healthy diet and physical activity [Summary of Diabetes Self-Care Activities (SDSCA)]), and self-reported HbA1c. Interaction effects tested whether associations varied by self-esteem (Rosenberg Self-Esteem Scale [RSES]), self-efficacy (Confidence in Diabetes Self-Care [CIDS] scale), or diabetes-specific social support (Diabetes Support Scale [DSS]).Significant positive associations were observed between DSAS and PHQ-8, GAD-7, and PAID across diabetes type/treatment groups (all P < 0.001), whereby each SD increase in DSAS scores was associated with approximately one-half SD deterioration in emotional well-being. Associations between DSAS and SDSCA and HbA1c were nonmeaningful. Self-esteem moderated psychological outcomes among participants with type 1 and non-insulin-treated type 2 diabetes and diabetes distress among those with insulin-treated type 2 diabetes. Interaction effects were partially observed for social support but not for self-efficacy.This study provides evidence of the association between diabetes stigma and depressive/anxiety symptoms and diabetes distress and for the moderating effects of self-esteem and social support among adults with type 1 and type 2 diabetes. Further research is needed to examine associations with objectively measured behavioral and clinical outcomes.