TNF and Insulin resistance: Taking into account that IL-6 has been proposed as an energy sensor within muscles (especially for muscle glucose uptake) [64], that Metrnl promotes an anti-inflammatory environment, improves glucose metabolism and reduces insulin resistance (IR) [62,63]; and considering that in our mice aging decreased the mRNA expressions of Glut1 and Glut4 and increased the expression of Tnf-α, the decreases observed in the expression of these myokines seems coherent.