Introduction: Type 2 diabetes, with its high prevalence, is associated with numerous complications. Diabetes management involves the use of glucose-lowering medications, insulin, and lifestyle modifications. However, self-medication of diabetes by patients is common and may lead to significant complications. Understanding the prevalence and causes of this phenomenon can  develop strategies to address it. Materials and Methods: A cluster sampling method was used to study 2,280 individuals in Kashan, Iran, to assess the prevalence of diabetes, related background factors, the prevalence of self-medication, and its types and causes based on self-reported data. Statistical analyses were performed using SPSS software. Results: The prevalence of type 2 diabetes among adults in Kashan was 12.63%. Significant differences were observed in terms of age, gender, education level, marital status, and employment status (P<0.001). The prevalence of self-medication was 62.15%. No statistically significant association was found between self-medication and gender, age groups, and education level. Self-medication was higher among married (P=0.028) and employed participants (P=0.003). The most common forms of self-medication were the use of herbal products, followed by refilling prescriptions without consulting a physician. The primary reasons for self-medication included high medication costs, expensive laboratory tests, costly physician visits, and limited insurance coverage. Conclusion: The prevalence of type 2 diabetes and self-medication among diabetic patients in Kashan is high, primarily due to high treatment costs and inadequate insurance coverage. Future research should focus on community-based interventions and evaluating the effectiveness of educational programs in reducing self-medication.