INS and obesity due to melanocortin 4 receptor deficiency: On the one hand, three major sources of proinflammatory cytokines have been suggested to affect beta cell function, insulin secretion, and/or insulin sensitivity in T2D: (i) from islet cells; (ii) from increased numbers of islet infiltrating macrophages/immune cells; (iii) from inflamed white adipose tissue, as a consequence of obesity, physical inactivity, and adipose tissue dysfunction [8,14,19].