Inflammatory Factors Associated with Late-Life Depressive Symptoms in Oldest-Old Patients with Type 2 Diabetes

While many studies indicate a bidirectional relationship between type 2 diabetes (T2DM) and depression, its precise nature remains unclear. The aim of the study was to determine the levels of inflammatory markers in oldest-old patients with diabetes and depressive symptoms and identify the risk factors associated with late-life depressive symptoms. In total, 195 participants with diabetes, aged 85 and above, were screened for depressive symptoms using the 30-item Geriatric Depression Scale (GDS-30). Clinical and biochemical data were also collected. Serum levels of inflammatory markers were measured via enzyme-linked immunosorbent assay (ELISA). Serum levels of TNF-α, IL-1β, and IL-6 were increased in individuals with depression and correlated with each other as well as with HbA1c levels, GDS scores, FBG and BMI. The multivariable analysis confirmed that of the three studied biomarkers, only TNF-α is independently associated with depressive symptoms when adjusting for demographic factors (Model 1) and cardiovascular burden (Model 3); however, its significance disappeared when controlling for glycaemic parameters (Model 2). Only TNF-α is independently associated with depressive symptoms in oldest-old patients with T2DM, though this relationship is tightly dependent on glycaemic control. Future studies should clarify whether IL-1β and IL-6 contribute to depressive symptoms through distinct pathophysiological pathways.