In order to further investigate the relative influence of BMI on serum apelin levels, we stratified our whole population (T2D and controls) in three groups of normal-weight (BMI = 20–24.9 Kg/m2), overweight (BMI: 25–29.9 Kg/m2) and obese (BMI>30 Kg/m2) subjects and found significantly increased apelin levels in presence of higher BMI (0.82±0.58 ng/mL in normal-weight, 1.01±0.87 ng/mL in overweight, 1.3±1.2 ng/mL in obese subjects, trend test P = 0.03). Here, APLN is linked to type 2 diabetes mellitus.