While STAT3 GOF variants have been shown to lead to early‐onset diabetes by affecting the regulation of immune‐related cells, recent studies demonstrate that activating variants in STAT3 can also affect insulin secretion, pancreatic β‐cell function, and pancreatic development (Kostromina et al., 2010; Saarimaki‐Vire et al., 2017; Velayos et al., 2017). This evidence concerns the gene STAT3 and diabetes mellitus.