Purpose <p>There has been evidence linking dioxin and metabolic disorders, including diabetes. Despite diet being the primary route of dioxin exposure, research assessing dioxin exposure risks using dietary values is still lacking. We aimed to illustrate the risk of dioxin in diabetes by utilizing calculated dioxin dietary intake and blood dioxin concentration values in the Korean population.</p> Methods <p>The present study included 202 subjects aged 20–69 undergoing medical evaluations at the Severance health check-up [prediabetes/diabetes (<i>n</i> = 92) <i>vs</i>. control (<i>n</i> = 110)]. Nutritional information for dioxin reduction was provided every month for one year. At baseline and 1-year after points, dioxin concentrations (pg TEQ/g-lipid) in serum were analyzed, and a short version of the food frequency questionnaire with 52 food items was used to calculate dioxin dietary intake.</p> Results <p>Strong associations between serum total dioxins, polychlorinated dibenzo-para-dioxins, polychlorinated dibenzofurans, and dioxin-like PCBs (DL-PCBs) concentrations and prediabetes/diabetes risk were observed (all ORs &gt;1.0). Mediation analysis further showed that diastolic blood pressure, high-density lipoprotein-cholesterol, and glucose partially mediated these associations (proportion 11–30%, all <i>p</i> &lt; 0.05). A dietary pattern rich in fish/seafood, meat, eggs, and supplements was positively correlated with serum DL-PCBs in the prediabetes/diabetes group (<i>r</i> = 0.353, <i>p</i> = 0.001). Furthermore, nutrition education has the potential to reduce dioxin dietary intake.</p> Conclusion <p>If the effectiveness of nutritional education is clearly verified through follow-up research, it can also reduce the risk of dioxin-induced metabolic disorders shown in cross-sectional analyses of baseline data.</p>