Elevated remnant cholesterol levels and variability with incident mental disorders in adults with type 1 diabetes: a nationwide cohort study.

AIMS/HYPOTHESIS: Elevated remnant cholesterol (RC) levels have been implicated in low-grade inflammation and may contribute to depressed mood. We examined the association between RC levels and variability in the incidence of psychiatric disorders in adults with type 1 diabetes using a nationwide cohort. METHODS: This study enrolled adults with type 1 diabetes who participated in the Korean National Health Screening Program between 2009 and 2015, who were divided into quartiles based on baseline RC. RC variability was assessed using standard deviation (SD), coefficient of variation, variability independent of the mean, and average real variability (ARV). The primary endpoint was the incidence of composite mental disorders, including depression, bipolar disorder, persistent affective and other affective disorders, or anxiety- and stress-related disorders. Associations were assessed using Cox proportional hazard models. RESULTS: Among 10,523 participants (median follow-up of 6.2 years), the highest RC quartile had a significantly higher risk of composite mental disorders than the lowest quartile (adjusted hazard ratio [aHR] 1.43; 95% confidence interval 1.29-1.58). Corresponding aHRs were 1.45 (1.25-1.67) for depression, 1.38 (1.07-1.77) for bipolar disorder, persistent affective and other affective disorders, and 1.41 (1.25-1.58) for anxiety- and stress-related disorders. Higher RC variability, particularly SD and ARV, was independently associated with an increased risk of composite mental disorders and anxiety- and stress-related disorders. CONCLUSIONS: Elevated RC levels were associated with a higher risk of incident mental disorders. RC from routine lipid profiles may identify adults with type 1 diabetes needing closer mental health assessment, pending prospective validation.