Objective: To explore the related factors of type 2 diabetes mellitus (T2DM) in overweight and obese children and adolescents, so as to provide scientific evidence for early screening and making targeted comprehensive prevention and control strategies. Methods: A total of 332 overweight and obese children and adolescents aged 6-18 years who visited the department of pediatric endocrinology of a tertiary hospital in Liaoning Province from February 2023 to July 2025 were selected. A case control design was adopted, and the subjects were divided into the case group (overweight/obese children and adolescents with T2DM, n =166) and the control group (overweight/obese children and adolescents without diabetes, n =166) based on 1∶1 propensity score matching. Information on demographic characteristics, dietary and lifestyle behaviors was collected through questionnaires. Multivariate Logistic regression analysis was used to analyze the related factors of T2DM in overweight and obese children and adolescents. Results: The average body mass index of overweight and obese children and adolescents was (28.50±5.23)kg/m 2. Multivariate Logistic regression analysis showed that family history of diabetes ( OR=6.71, 95%CI =3.35-14.05), age at onset of weight gain <6 years ( OR=4.08, 95%CI =2.13-8.13), hyperphagia ( OR=2.46, 95%CI =1.25-4.97), and preference for fried foods ( OR= 2.42 , 95%CI =1.21-4.99) were associated with an increased risk of T2DM in overweight and obese children and adolescents (all P < 0.05). In contrast, vitamin D supplementation during pregnancy ( OR=0.50, 95%CI =0.25-0.99), frequent sun exposure during pregnancy of mothers ( OR=0.48, 95%CI =0.24-0.97), breastfeeding ( OR=0.35, 95%CI =0.18-0.66), vitamin D supplementation after 3 years of age ( OR=0.31, 95%CI =0.14-0.68), and active commuting to school ( OR=0.29, 95%CI =0.15-0.58) were associated with a reduced risk of T2DM in overweight and obese children and adolescents (all P <0.05). Conclusions The occurrence of T2DM in overweight and obese children and adolescents is closely related to early onset obesity, genetic background, dietary behaviors, and physical activity. A continuous comprehensive prevention and control strategy from pregnancy to school age should be established to reduce the risk of the disease.