Recently, the challenge of developing small-molecule inhibitors of protein tyrosine phosphatase 1B (PTP1B) has resulted in intense research; it can be considered a novel target for T2DM and its inhibition as a point of intervention could provide a new therapeutic option to patients with at-risk obesity or T2DM. Here, PTPN1 is linked to obesity due to melanocortin 4 receptor deficiency.