Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 53 7 2024 07 07 1508 1516 Seong-Hi Park School of Nursing, Soonchunhyang University, Asan, South Korea Heashoon Lee School of Nursing, Hannam University, Daejeon, South Korea 2022 07 22 2023 04 07 Background: Diabetes mellitus (DM) has different prevalence by region. This study aimed to identify the differences in the effects of obesity and depression on DM in South Korean adults by region. Methods: The participants were 14,343 adults (≥30 yr) from Ulsan (regions with the lowest prevalence of DM) and Jeonbuk (regions with the highest prevalence of DM), and data were extracted from the Community Health Survey 2019. We applied a complex sampling design analysis to reflect the stratified, clustering and weights. The data were analyzed using the unweighted frequencies, weighted percentage, mean, standard error, Chi-Square test and multiple logistic regression analysis (SPSS 25.0). Results: Regarding the main result for Ulsan, the odds ratio of DM increased by 1.94, 2.52,1.57, and 4.87 times for obesity(25-29.9kg/m²), high obesity(≥30kg/m²), depression, and receipt of psychological counseling for depression, respectively. In Jeonbuk, the odds ratio of DM increased by 1.79, 2.84, and 3.59 times for obesity, high obesity, and unmet medical experience, respectively. On the other hand, depression-related variables were found to not influence DM Conclusion: We provided the rationale for conducting a health project that interventions for obesity and depression should be included in DM management programs differently in Ulsan and Jeonbuk regions. https://ijph.tums.ac.ir/index.php/ijph/article/view/29382 https://ijph.tums.ac.ir/index.php/ijph/article/download/29382/8283