Chromium picolinate reduces insulin resistance in polycystic ovary syndrome: Randomized controlled trial. 

Published in 2016 this double blinded randomized controlled trial (RCT), conducted on 85 female PCOS patients (20–35 years old) to assess the effects of chromium supplementation on fasting glucose insulin ration, BMI, fasting blood sugar. The treatment group did demonstrate a significant reduction in fasting serum insulin levels.  

References:

Ashoush S, Abou-Gamrah A, Bayoumy H, Othman N. Chromium picolinate reduces insulin resistance in polycystic ovary syndrome: Randomized controlled trial. J Obstet Gynaecol Res. 2016 Mar;42(3):279-85. doi: 10.1111/jog.12907. Epub 2015 Dec 14. PMID: 26663540. https://pubmed.ncbi.nlm.nih.gov/26663540/