Diabetes mellitus (DM) is a growing global public health concern, including Thailand. Prior research has established an association between fatty liver disease (FLD) and DM. Moreover, the distribution of DM was also found in liver fluke endemic areas where praziquantel (PZQ) was used prevalently. However, limited information exists regarding factors associated with DM, specifically in FLD patients undergoing PZQ treatment. Our study aimed to evaluate the association between the combination of PZQ treatment and FLD diagnosis, and DM in Northeast Thailand. We conducted the study among participants in northeastern Thailand with self-reported DM diagnosis and PZQ treatment history using health questionnaires. Additionally, FLD diagnosis was confirmed through ultrasonography from the Cholangiocarcinoma Screening Program data collected from 2013-2022. We employed multilevel mixed-effect logistic regression to assess the association between the combination of PZQ treatments and FLD diagnosis, and DM, represented as adjusted odds ratios (AOR) and their 95% confidence intervals (CI). Of 756,431 participants, the overall DM prevalence was 7%. Notably, 10.45% of individuals with FLD+ and 8.23% with PZQ+ were found to have DM. Specifically, the prevalence of DM in individuals with PZQ+ and FLD-, PZQ- and FLD+, and PZQ+ and FLD+ combinations were 7.14%, 10%, and 11.81%, respectively. In comparison to PZQ- and FLD-, participants with PZQ+ and FLD-, PZQ- and FLD+, and PZQ+ and FLD+ were associated with DM (AOR = 1.27; 95% CI: 1.24-1.30, AOR = 1.8; 95% CI: 1.76-1.85, and AOR = 2.19; 95% CI: 2.12-2.27, respectively). In conclusion, the combination of PZQ and FLD plays a crucial role in the association with DM, particularly in individuals with PZQ+ and FLD+. Our findings emphasize the importance of DM screening, with special attention to individuals with a combination of PZQ treatment and FLD diagnosis, in order to promote early detection and management of DM in Northeast Thailand.