Background Diabetes mellitus (DM) is a chronic disease with debilitating complications. Patients with diabetes are recommended to take various self-management decisions and carry out complex care activities. Diabetes self-management education (DSME) and support help people with diabetes to take these decisions and activities to improve health outcomes. DSME may serve as the basis to minimize and avoid catastrophic diabetes-related complications and the resulting financial and personal costs associated with this disorder. We aimed to assess the effect of diabetes self-management education program on glycemic control on patients with diabetes. A quasi-experimental pre-post study was conducted at the family medicine clinic in Suez Canal University hospital, Ismailia, Egypt. A total of 116 patients with uncontrolled DM were recruited by a simple random technique after applying the inclusion and exclusion criteria. Participants were subjected to a 12-week health education program (1 session/week). The sessions focused on areas of diabetes self-management based on the American Diabetes Association (ADA) guidelines. The glycosylated hemoglobin (HbA1c) was assessed at baseline and again at the end of the program. Also, self-care activities were evaluated pre-post intervention using the Arabic version of the Summary of Diabetes Self-Care Activities (SDSCA) instrument which measured the activities related to diet, exercise, blood sugar testing, foot care, and medications. Results The mean age of participants was 47 years (± 11.54), male patients represented 54%. About two-thirds (67%) were from urban areas and came from a middle socioeconomic level. About half of the participants (51.7%) were diagnosed as diabetics for 5–10 years duration. More than half (52.7%) were on combination therapy of insulin and oral antidiabetic drugs. After the intervention program, there was a statistically significant decrease in HbA1c level (p value < 0.001), and 21% of the participants reached the ADA treatment goal for HbA1c below 7. Conclusion Appropriate DSME programs are practical and have a benefit to patients with diabetes.