Introduction: Diabetes mellitus is still a serious global public health concern, especially in underdeveloped nations where there is still a lack of knowledge and efficient treatment. Effective glucose control and the avoidance of complications depend on patients having enough information and self-management skills. Objective: This study assessed the knowledge, management practices, and control of diabetes mellitus among diabetic patients attending the Federal Medical Centre, Gusau, Zamfara State, Nigeria. Methods: The study employed a descriptive cross‑sectional study design among patients diagnosed with diabetes mellitus attending the outpatient clinics of the Federal Medical Centre, Gusau. A standardised questionnaire measuring sociodemographic traits, diabetes knowledge, management techniques, and self-care behaviours was used to gather data. The results were summarised using descriptive statistics. Results: Patients' awareness of the causes, symptoms, and complications of diabetes varied according to the study. There were still gaps in understanding on blood glucose self-monitoring, lifestyle change, and complication avoidance, even though many respondents understood the significance of medication and dietary control. Conclusion: The results highlighted that despite patients' basic understanding of diabetes, there are substantial gaps in their self-management and disease control behaviours. Improving patient counselling services and bolstering diabetes education initiatives in medical facilities may improve disease management and lower complications.