The associations of serum levels of leptin and irisin with depressive symptoms were investigated in elderly patients with type 2 diabetes (T2DM).<h4>Methods</h4>189 elderly diabetics were assessed with the 30-item Geriatric Depression Scale (GDS-30), and 57 patients with depressive symptoms and 132 controls were selected. This evidence concerns the gene FNDC5 and type 2 diabetes mellitus.