What does Insulin do for bodybuilders?

Why do body builders use insulin? Does it digest the protein quickly? Does it make them bigger, stronger?

Insulin is an anabolic hormone... When bodybuilders or athletes use it it has effects on all sorts of tissues including glucose and amino acid uptake into your muscles. It is tricky and dangerous though because it can make you overly hypoglycemic if you take too much or fudge your diet. Without insulin your bodies natural tendency is to break things down for energy... think of it that way.

It helps drive nutrients like protein and supps like creatine into the muscles better post-workout.