Aim <p>Illness perception shapes how individuals understand their disease and symptoms, affecting treatment behaviors and medication adherence. Fatalistic beliefs are linked to poor adherence and reduced quality of life. This study set out to determine the relationship between fatalism and illness perception in diabetes patients.</p> Method <p>This study employed a cross-sectional design involving 232 patients diagnosed with Type 2 diabetes mellitus. Data collection took place between April and September 2024 using the Patient Information Form, the Diabetes Fatalism Scale, and the Brief Illness Perception Questionnaire. Data were analyzed using descriptive statistics, independent samples t-test, one-way analysis of variance (ANOVA), pearson correlation analysis, and multiple linear regression analysis.</p> Results <p>A total of 232 individuals with Type 2 diabetes participated in the study (mean age: 51.69 ± 14.11 years; 55.6% female).The findings indicated that participants demonstrated moderate levels of both illness perception and fatalistic beliefs. A significant negative association was observed between the Diabetes Fatalism Scale and Brief Illness Perception Questionnaire scores (<i>r</i> = -0.360, <i>p</i> &lt; 0.01). Multiple linear regression analysis showed that diabetes fatalism remained significantly associated with illness perception after adjustment for gender, HbA1c level, family history of diabetes, and diabetes-related complications (β = -0.343, <i>p</i> &lt; 0.001). The overall model was statistically significant (F = 7.634, <i>p</i> &lt; 0.001) and explained 14.4% of the variance in illness perception (R² = 0.144).</p> Conclusion <p>Fatalistic beliefs are significantly associated with illness perception among individuals with diabetes. It is recommended that sociocultural factors affecting fatalism and illness perception be evaluated, and appropriate interventions be planned accordingly.</p>