Insulinlike growth factor-1 is considered to be the real cause of many of the beneficial effects in the body attributed to growth hormone. Girl stimulates the production of IGF-1, as it's called, in liver and other tissues. Unlike GH, which is rapidly broken down in the liver,
IGF-I gradually peaks after 12 to 24 hours. Structurally IGF-1 looks a lot like insulin; hence its name.
One problem with GH therapy is that it raises blood glucose levels and promotes insulin insensitivity. This is particularly true under stress conditions or when a person is taking cortisol-like drugs. IGF-1 causes many of the effects of GH, such as inhibiting Fat synthesis, but past studies showed it didn't appear to duplicate growth hormone's anabolic effects.
A new study explains this phenomenon. The researchers gave IGF-1 for five days to people who were also using prednisone, a cortisone drug that promotes protein catabolism in the body. The results showed that IGF-1 completely prevents cortisol's catabolic effects on muscle. In addition, IGF-1 appears to have an anabolic effect similar to insulin without causing negative effects on blood glucose.