Prevalence and Pathogenic Factors of Thyroid Dysfunction in First-Episode and Drug-Naïve Major Depressive Disorder Patients With Fasting Blood Glucose Abnormalities in Early- and Late-Onset Age.

Aims: This study aims to explore the mutual mechanisms and distinct pathogenic factors between fasting blood glucose (FBG) abnormalities and thyroid dysfunction (TD) in major depressive disorder (MDD) patients of different onset ages. Methods: One thousand seven hundred eighteen first-episode and drug-naïve (FEDN) MDD patients were selected. Hamilton Depression Rating Scale (HAMD), Hamilton Anxiety Rating Scale (HAMA), Positive and Negative Syndrome Scale (PANSS) positive subscale, Clinical Global Impression (CGI), FBG, and thyroid-stimulating hormone (TSH) were measured, along with other relevant biochemical indicators. Results: TD prevalence was 86.69% in early-onset MDD patients with abnormal FBG while in late-onset was 86.86%. No significant difference was found. The area under the curve (AUC) values of FBG detecting TD were all over 0.700. Depressive symptoms and lipid metabolites were significant risk factors and were more specific indicators for late-onset MDD patients with FBG abnormalities. Further binary logistic regression and receiver operating characteristic (ROC) curves revealed that depression severity, high-density lipoprotein cholesterol (HDL-C) predicted TD well in MDD patients with FBG abnormalities, making this predictive effect more significant in the late-onset group. Conclusions: Insulin resistance and lipid metabolism abnormalities based on FBG abnormalities significantly impact TD in late-onset MDD. Specificity and regular monitoring should be considered for different onset ages of MDD patients with abnormal metabolism. Further research should clarify the interactions among insulin resistance, lipid metabolism, and TD. The First Hospital of Shanxi Medical University Ethics Committee reviewed and approved this study (No. 2016-Y27).