The purpose of this study was to define the relationship of chemerin and TNF-α with mtDNA copy number in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT; mesentery of the small intestine (Mes), greater omentum (GO) and blood mononuclear cells (MNCs)) in obese patients with/without type 2 diabetes mellitus (T2DM). The gene discussed is RARRES2; the disease is diabetes mellitus.