Background <p>Medication adherence is crucial for managing chronic diseases, especially among the older adults who are at an increased risk of polypharmacy and nonadherence. This study aimed to evaluate the patterns of medication adherence among older adult patients with diabetes in Korea and identify the factors affecting these patterns.</p> Methods <p>Using data from the 2020 Korea Healthcare Panel, we analyzed 984 patients with diabetes aged ≥ 65 years. Medication adherence was assessed in three dimensions: dosage, frequency, and timing. The independent variables included sociodemographic factors, health status, and healthcare perceptions. Latent profile analysis and logistic regression were used to identify adherence patterns and determinants.</p> Results <p>The study population demonstrated high levels of medication adherence with average scores close to the ‘always adherent’ category across all dimensions. Two distinct adherence profiles were identified: “Adherent” (87.5%) and “Non-Adherent” (12.5%). Factors significantly influencing adherence included living alone, self-care ability, perceived stress, depression, and subjective health perception. Living alone, perceived stress, and positive health perception were correlated with higher adherence and self-care ability, and depression inversely affected medication adherence.</p> Conclusions <p>Older adult patients with diabetes in Korea show a high level of medication adherence. Medication adherence is multifactorial, highlighting the significant impact of non-medication factors in the older adult population.</p>