The diseases of diabetes and obesity have emerged as serious challenges in global public health, and adolescents are not exempt from this concern. These conditions not only impact physical health but also influence psychological well-being and overall quality of life. Modern lifestyles, characterized by unhealthy eating patterns and insufficient physical activity, contribute to the rising prevalence of both diseases among adolescents. Therefore, it is crucial to raise awareness and implement effective preventive measures among adolescents who are in a crucial stage of development. The objective of this outreach activity is to enhance participants' knowledge regarding the prevention of diabetes mellitus and obesity among teenagers.The method employed for this activity involves socialization with 45 teenage students. The event took place on January 18-19, 2024, at the Ikhsaniah High School Hall in Tegal City. The outcomes of the activity commenced with a pre-test, introduction, presentation of material, and discussion. In the first phase, a pre-test was conducted, revealing that 80.0% of students had insufficient knowledge. The second phase involved educational sessions, with the first covering the definition, risk factors, and prevention of diabetes mellitus. The second segment addressed obesity prevention, including the assessment of nutritional status through practical calculations. In the third phase, an evaluation was conducted, resulting in a notable increase in knowledge, with 90% improvement.