Objectives: This uncontrolled open study aimed to measure the levels of self-care of patients before and after education, their initial knowledge, and their knowledge two months after interacting with healthcare providers using the Summary of Diabetes Self-Care Activities (SDSCA) questionnaire. Methods: The data for this study were collected over 14 months from 396 patients with diabetes. This study was conducted in three phases: initial questionnaire testing, education, and retesting after two months. The education included specific diabetes-related topics: nutrition, exercise, self-monitoring of blood glucose, foot care, and smoking. Results: The results showed that all self-care activities between the first and second assessments were different. The initial assessment showed that the more successful the general diet, the specific diet, and physical activity were, the better the hemoglobin A1c value was. When considering the impact of gender on self-care effectiveness results, it was noted that women were more successful in foot care and specific diet in the initial testing, while men excelled in physical activity. The most successful age group in the scales of general diet, physical activity, and blood glucose testing was 31–45 years. Those with type 1 diabetes (36% of the study population) were more successful in self-care in the first and second measurements but without any differences in self-care in the retesting. Conclusions: our study observed a difference in self-care results between the two measurements of self-care activities in patients with diabetes, evaluated by the SDSCA questionnaire.