Background: Diabetes mellitus (DM) is a major metabolic disorder currently affecting over 350 million people worldwide. Also, another one billion people in the world are pre-diabetic, who may eventually end up with full- blown diabetes. Type 2 diabetes mellitus is fast becoming a global epidemic and the number of individuals with diabetes in the world is expected to reach 330 million by 2030. The rate of T2DM is rapidly increasing in developing countries, particularly among younger age groups A cross-sectional study indicated that Saudi adolescents exhibited more health-related knowledge than the older population; the majority of the adolescents believed that obesity was dangerous and that regular exercise was beneficial for their health. According to the International Diabetes Federation. Saudi Arabia is a developing country with a young population (53% ≤24 years old). Saudi adolescents are at a high risk of developing diabetes as many suffer from obesity, a sedentary lifestyle and hereditary diabetes. In 2004, almost a quarter (23.7%) of the Saudi population was diagnosed with T2DM; this was 10 times the number of diabetic individuals in 1980.6 The occurrence of T2DM has been linked to the high rate of overweight adults (35.5%) in the Saudi population and the number of overweight and obese Saudi adolescents is high among both genders. Aim of the study: The study aimed to assess the level of knowledge and awareness of DM among secondary school students at the Makkah in Saudi Arabia 2022. Method: cross sectional descriptive study conducted among secondary school students at Makkah, during the April to June, 2021, the Sample size of diabetic secondary school students. Our total participants were (600). Results: a significant positive correlation between Knowledge and Awareness were r= 0.670 and p-value =0.001, the participants (58.33%) were in the age group more than 16 years the data ranged from(12.5-18) by mean ±SD(14.849±2.035),the majority of them were males (61.67%) . Conclusion: This review highlights the need for increased knowledge and awareness of DM among the Saudi students. Raising adolescents’ awareness about the primary prevention strategies for T2DM should be a public health priority in Saudi Arabia. The HBM could inform further research on diabetes prevention among Saudi adolescents. The means of improving knowledge and awareness of DM needs to be integrated into existing healthcare systems and processes to better inform patients, families, and communities about this chronic disease. Keywords: Diabetes mellitus, knowledge, awareness, secondary, school, students, Saudi Arabia