The transitioning from using insulin from pigs and cows to using transgenic insulin for type 1 diabetic people could be possibilities of some adverse effects and some uncertainties about the new insulin. For a long period of time, the insulin that was being used, was obtained from the pancreas of cows and pigs and said to had caused some allergic reactions. In 1955 it changed to transgenic insulin, also known as human insulin, which was said to less likely to trigger allergic reactions. Since both yeasts and bacteria reproduce quickly than complex mammals, they grow at a low cost then the sources of beef and pork insulin. Their quicker pace negates the delay related to the maturing of sources from animals, also the area required to support
