In addition to oligonucleotide therapeutics, some small-molecule NNMT inhibitors have been reported recently [56–59] and several have shown effectiveness in the prevention or treatment of obesity and T2D in vitro [60, 61] or in preclinical animal models [10, 58, 62], validating NNMT as a pharmacological drug target. This evidence concerns the gene NNMT and obesity due to melanocortin 4 receptor deficiency.