INS and obesity due to melanocortin 4 receptor deficiency: In other clinical trials, the role of tadalafil (Cialis or Adcirca)/Eli Lilly was determined in context of type 2 diabetes (postprandial hyperglycaemia) (NCT01238224, phase I/terminated early 2011), obesity (NCT0255404, phase IV/completed 2015), insulin resistance in type 2 diabetes (NCT02601989, phase II), diabetic cardiomyopathy (NCT01803828, phase IV) [170,186,187], whereas sildenafil caused an increase in peripheral insulin sensitivity to insulin in patients with pre-diabetes after 3 months of treatment [168].