Objectives: The objective is to assess knowledge, attitude, and practice toward diabetes mellitus (T2DM) and its association with socioeconomic status among adult patients with T2DM.Methods: This cross-sectional study used the validated “Diabetes Knowledge Test (DKT)” questionnaire obtained from the Michigan Diabetes Research Center. A translated copy into Arabic has been validated and used in another study. The questionnaire was created on Google Forms and distributed through digital platforms to collect data from patients with T2DM in Saudi Arabia.Results: In this study, the majority were female (63.4%), and Saudi Arabians (96.5%), among them 23.7% lived in Riyadh, and 42.8% were from the central region. As for marital status, 60.5% were married, 28.4% were single, and 11.1% were divorced or widowed. 58.9% had college/higher degrees, and 45.8% were unemployed. Furthermore, the majority (47.1%) reported having a salary of less than 5,000 Saudi Riyals per month. 55.1% of participants lived in villas, while 46.6% had 6-10 people living in their household. Generalized linear model (GLM) findings showed that age, marital status, level of education, monthly income, and accommodation are significantly correlated with the level of knowledge.Conclusion: Findings indicated a high level of knowledge, positive behavior, and good adherence to practice among patients with T2DM. GLM findings showed that age, marital status, level of education, monthly income, and accommodation are significantly correlated with the level of knowledge. Researchers suggest that effective health education interventions are needed to improve diabetes knowledge, behavior, and practices, particularly regarding lifestyle modifications and dietary management.