Background, Diabetes Mellitus has very serious complications among children and adolescents worldwide. Management of Type 1 Diabetes (T1D) carriages numerous challenges, especially for young children and their families. So, the application of the biopsychosocial model was suggested to help in comprehensive diabetes care. The purpose of this study was to assess the effect of the bio-psychosocial model on parents' self-efficacy and coping strategies among children with type 1 Diabetes Mellitus. A quasi-experimental research design was used (pre, post, and follow-up tests). The setting, this study was led in private Out-Patient Clinics. Sample, a purposive sample of 60 diabetic children with (type 1 diabetes) and their parents were involved. Three instruments were used: I- structured interviewing questionnaire including (characteristics of children and their parents), Adjustment of children, children's adherence to a diabetes regimen, and parents' knowledge. II- Children's coping strategies inventory. III- Parents' self-efficacy Likert Scale. The results showed that 43.3% and 78.3% of parents had a higher level of knowledge about diabetes and its complications on the post and follow-up tests(respectively) than 13.3% on the pre-test. As well, children had a moderate level of coping on post-test and follow-up. Also, the findings revealed that 86.7% of parents of the studied children had a high level of self-efficacy on post-test and follow-up tests compared to 55.0 % on the pre-test. The study concluded that the implementation of the biopsychosocial model had an important effect on parents' self-efficacy and coping strategies among children with type 1 diabetes mellitus. So, it was recommended that the Biopsychosocial health education model must be applied in all pediatrics departments and pediatric intensive care units to improve the quality of care provided for children having diabetes.