FGF21 and obesity due to melanocortin 4 receptor deficiency: Actually, despite of FGF21 reduction in type 1 diabetes and latent autoimmune diabetes in adults (LADA) [12], circulating FGF21 levels were elevated in obesity [13], type 2 diabetes [14], dyslipidemia [15] and non-alcoholic fatty liver disease (NAFLD) [16].