<p>Diabetes is a common, controllable, and chronic disease. Today, a new approach in different countries to better control diabetes and its complications is proper self-care training for diabetic patients. This study aimed to investigate the effect of self-care training on the management of diabetic patients. This descriptive and analytical study with an intervention approach was conducted on 90 patients with type 1 diabetes. For this purpose, the participants were randomly divided into intervention and control groups. The training took about 4 h and was given to the patients directly and indirectly. Three months after the intervention, the results were evaluated. Three months after the intervention, the intervention group had significantly higher levels of quality of life, physical activity, foot care, dietary adherence, and medication adherence (<i>P</i> &lt; 0.05) and reported lower mean levels of glycosylated hemoglobin (HbA1c) and fasting blood sugar (FBS) than the control group (<i>P</i> &lt; 0.01). Also, there was no significant difference in the average self-care score in the control group before and 3 months after the intervention (<i>P</i> &gt; 0.05). Diabetes self-management education for children and adolescents showed positive effects on diabetes control, including a significant decrease in serum levels of FBS and HbA1c, as well as a substantial increase in the average quality of life and physical activity, foot care, and adherence to diet and medication. Therefore, it is recommended that in addition to drug therapy, self-care training should be offered and taken more seriously by doctors and health care providers.</p>