Background: Individuals living with diabetes mellitus (DM) often face psychological distress because of the disease's chronic progression and the complexity of its daily management. Distress has been linked to poor glycemic control and decreased quality of life. Therefore, these psychological distresses require social support. This study aimed to investigate the relationship between social support, psychological distress, and quality of life in patients with diabetes mellitus living in the community. Methods: A cross-sectional quantitative study was conducted with 250 diabetic patients recruited from five public health centers in Central Java, Indonesia using purposive sampling. Patients with severe cognitive impairment, psychiatric disorders, or comorbid conditions that could significantly affect psychological status were excluded. Data were collected through validated instruments: the Multidimensional Scale of Perceived Social Support (MSPSS), the Diabetes Distress Scale (DDS-17), and the World Health Organization Quality of Life-BREF (WHOQOL-BREF). The data were analyzed using Spearman’s rank correlation, and statistical significance was determined at p < 0.05. Results: The findings revealed a significant negative correlation between social support and diabetes-related distress (r = -0.48, p < 0.001), and a significant positive correlation between social support and quality of life (r = 0.55, p < 0.001). Conclusion: There was a significant association between social support and reduced distress as well as enhanced quality of life in community-dwelling individuals with diabetes. Nursing interventions that enhance family involvement, peer support, and community engagement are essential in diabetes management. These findings highlight the importance of psychosocial components in chronic disease care.