Self-efficacy has important theoretical and practical applications for health promotion and disease prevention among older adult. The present study aimed to evaluate the effect of an educational program on self efficacy for patients with type 2 diabetes mellitus. The study was conducted at outpatient clinic at Benha University Hospital in kaluobia governorate. The study was applied on 50 adult patients with type 2 diabetes mellitus aged between 20-50 years selected randomly from both sexes without disabilities and who can at least read and write. Data were collected through an interview questionnaire including (socio-demographic data and medical history), an interviewing questionnaire including (Patient’s knowledge & practice), and Diabetes Management Self-Efficacy Scale (DMSES). The results of the study concluded that there were highly significant statistical differences in total knowledge, practice, and self efficacy scores of the studied sample after implementation of the educational program, an extremely statistical significant difference was found in mean scores of glycosylated hemoglobin (HbA1c) levels after applying the educational program. The study recommended that further programs with continuous follow up for peoples with diabetes should be applied in all health care centers to help them to improve their self care behaviors and self efficacy.