IGFBP1 and polycystic ovary syndrome: Dou et al. found that cinnamon extract could reduce the plasma IGF-1 level, increase the plasma IGFBP-1 level, and downregulate the serum levels of testosterone and insulin, followed by restoring the estrous cyclicity and ovary morphology of DHEA-induced PCOS mice (Dou et al., 2018).