INS and obesity due to melanocortin 4 receptor deficiency: While some mechanisms of pathogenesis leading to comorbidity in an obesity or obesity-like state in mammals remain unknown, studies with mice and humans have revealed increased inflammation, aberrant cell signaling, decreased insulin sensitivity, and increased oxidative stress to be involved (Xu et al. 2003; Furukawa et al. 2004; Montague et al. 1997).