"Men with androgenic alopecia typically have higher levels of 5-alpha-reductase, lower levels of total testosterone, higher levels of unbound/free testosterone, and higher levels of total free androgens including DHT"
"5-alpha-reductase is responsible for converting free testosterone into DHT. The genes for 5-alpha-reductase are known.[12] The enzymes are present predominantly in the scalp and prostate. Levels of 5-alpha-reductase are one factor in determining levels of DHT in the scalp and drugs which interfere with 5-alpha-reductase (such as finasteride, which inhibits the predominant type 2 isoform) have been approved by the FDA as treatments for hair loss.
Sex hormone binding globulin (SHBG), which is responsible for binding testosterone and preventing its bioavailability and conversion to DHT, is typically lower in individuals with high DHT. SHBG is downregulated by insulin.
Increased levels of Insulin Growth Factor-1 (IGF-1) have been correlated to vertex balding.[13]
High insulin levels seem the likely link between metabolic syndrome and baldness. Low levels of SHBG in men and non-pregnant women are also correlated with glucose intolerance and diabetes risk, though this correlation disappears during pregnancy
