INS and obesity due to melanocortin 4 receptor deficiency: The models differ in the animal species and the induction method used (eg.: genetically or chemically induced DM), in the underlying metabolic conditions (rate of hyperglycaemia reached, hyperlipidaemia, insulin homeostasis), the presence or absence of other concomitant pathology (eg.: hypertension, obesity), the duration of maximum observation period and the rate of vasculopathy.