PROK1 and polycystic ovary syndrome: It is known that metformin decreases insulin levels, although the treatment does not seem to prevent gestational diabetes in PCOS women.20 21 23 We recently demonstrated that insulin upregulates PROK1 in decidualising endometrial stromal cells in vitro.18 However, in this study, we found no correlation between s-PROK1 and insulin levels.