The Relationship of Triglyceride/Glucose Index with Disease Severity, Sleep, and Cognitive Functions in Patients with Geriatric Depression: A Comparative Cross-Sectional Study with Healthy Controls

Objectives This cross-sectional study investigated the association between the TyG index – a peripheral insulin resistance marker – and depression status, clinical severity, sleep quality, and cognitive functions in drug-naïve older adults compared to healthy controls.Methods Older adults aged 60–74 (mean: 66.2 ± 3.8, range: 60–74; 65.5% depressed) comprising 76 patients with MDD and 40 controls were evaluated using GDS-15, ISI, and SMMSE. Assessor-blinded to the clinical psychiatric status of the participants.Results The TyG index was significantly higher in patients than controls. Within the depressed cohort (n = 76), the TyG index correlated significantly with depression severity (r = 0.401, p < .001), but its cross-sectional associations with cognitive function (p = .110) and insomnia severity (p = .163) were non-significant. In multivariate logistic regression adjusted for age, sex, education, BMI, and comorbidities, the TyG index remained independently associated with higher odds of depression status (Exp(B)=24.935, p < .001). Exploratory ROC analysis revealed that a tentative cutoff of >8.78 discriminated depressed individuals with 63.16% sensitivity and 95.00% specificity (AUC = 0.804, p < .001).Conclusions The TyG index is cross-sectionallyassociated with depression status and clinical severity in drug-naïveolder adults, independent of BMI.Clinical implications The TyG index represents a cost-effective, noninvasive exploratory metabolic biomarker that may complement clinical screenings in late-life psychiatry.