Purpose <p>The prevalence of type 2 diabetes mellitus (T2DM) varies across countries. The present study aimed to examine factors contributing to differences in the prevalence of T2DM based on Global Burden of Disease (GBD) data and using a multilevel model.</p> Methods <p>Longitudinal data from 188 countries were obtained from GBD data and analyzed using multilevel models, with yearly observations nested within countries. Level 1 predictors included high body mass index (BMI), low physical activity (PA), and a diet low in fiber (DLF), and Level 2 predictors were human development index (HDI) and current health expenditure (CHE) as a percentage of gross domestic product (GDP). Both models incorporated fixed effects for all predictors. The first specified random intercepts for countries, while the extended model additionally included random slopes for time, high BMI, and low PA.</p> Results <p>The results of the first model showed that high BMI and low PA were significantly and positively associated with T2DM prevalence. CHE (% of GDP) showed a significant inverse association. The extended model also demonstrated that low PA and high BMI had a significant positive impact on the prevalence of T2DM. In addition, HDI showed a significant negative association, indicating that higher HDI was linked to lower T2DM prevalence.</p> Conclusions <p>The prevalence of T2DM is influenced by a complex interplay of both individual and country level determinants. Strengthening primary prevention across all levels, while considering countries’ development status and allocating adequate health expenditure, is essential to reducing the global burden of T2DM.</p>