SHBG and Insulin resistance: Based on the results above, the effect of metformin on testosterone, androstenedione, and SHBG can be judged: metformin has a positive effect on reducing the risk of LBW-PP girls developing into PCOS.[34–37] By reducing insulin resistance in the liver, decreasing androgen secretion by adrenal glands and ovaries, and increasing the production of SHBG in the liver, metformin takes effect in girls, thus reducing free testosterone concentrations.[38–40]