Sex Hormone Binding Globulin (SHBG) is reduced in insulin resistance and actually a very good marker for insulin resistance

"SHBG is reduced in insulin resistance and actually a very good marker for insulin resistance.
Many women with polycystic ovarian syndrome have a high-normal or even a normal total
testosterone but have a low SHBG because they have insulin resistance. Therefore, their
bioavailable testosterone is often on the high side."

Source: "www.goodhormonehealth.com/SHBG and polycystic ovarian syndrome (PCOS).pdf"