Igf may cause an effect on blood sugar, creating a feeling of hypoglycemia shortly after a shot, but it should have no effect on your body's ability to produce and maintain insulin - i.e., it won't make you diabetic.

Stem cell differentiation, there's some college level biology for you. The primary effect we are interested in is IGF can cause hyperplasia of the muscle cells, meaning it may increase the number of muscle cells. Muscle cells, like fat cells, will grow before they multiply. It takes quite a bit of work to create new cells. IGF will create new cells, which in turn leads to bigger denser muscles due to more cells growing in size.