INS and obesity due to melanocortin 4 receptor deficiency: Oxidative stress has been evidenced during the development of obesity with elevated levels (urinary, systemic and/or tissue-specific) of biomarkers such as 8-epi-Prostaglandin F2α (8-iso-PGF2α), 4-Hydroxynonenal (4-HNE) and MDA in children and adults [50,51], insulin-sensitive and insulin-resistant patients with obesity [52,53,54,55,56,57].