Personality Traits, Psychiatric Symptoms, and Glycemic Control in Patients with Type 2 Diabetes Mellitus: A Cross-Sectional Study

Background: Diabetes mellitus (DM) management is influenced by both physiological and psychosocial factors. Personality traits and psychiatric symptoms may affect glycemic control, but their exact relationship remains unclear. This study aimed to evaluate the association between glycemic control, personality traits, and psychological symptoms such as depression, anxiety, and stress in patients with DM. Methods: A total of 174 adult patients with Type 2 DM (T2DM) were included. Glycemic control was assessed via HbA1c values over one and five years. Personality traits were measured using the Personality Belief Questionnaire-Short Form (PBQ-SF), and psychiatric symptoms were evaluated with the Symptom Checklist-90-Revised (SCL-90-R). Patients were grouped based on HbA1c levels: good (<7%), moderate (7–9%), and poor (>9%) control. Results: Significant differences were found in several personality traits, including obsessive-compulsive, histrionic, paranoid, passive-aggressive, antisocial, and schizoid traits, between groups, with higher scores in patients with moderate glycemic control compared to those with poor control. No significant relationship was observed between psychiatric symptoms and glycemic control. The proportion of patients meeting the predefined HbA1c follow-up frequency threshold was lowest in the poor control group. Conclusions: General psychiatric symptoms did not show significant differences across glycemic control groups. Several maladaptive personality traits differed between groups in univariate analyses; however, after adjustment for potential confounders, only passive-aggressive personality traits remained independently associated with HbA1c levels. These findings indicate a possible association between specific personality characteristics and glycemic control, although no direct clinical utility can be inferred from the present data. Further longitudinal studies are required to clarify these relationships.