INS and type 2 diabetes mellitus: In humans, preptin levels appear to increase with increased circulating insulin or impaired glucose tolerance, such as in obesity, type 1 and T2DM, gestational diabetes mellitus, and polycystic ovarian syndrome.(12, 13, 14, 15, 16, 17, 18, 19, 20) Aside from the associations identified in these observational studies, little is understood about the effects of endogenous preptin on whole‐body glucose metabolism.