Humulin

For A project I researched biotechnological milestones in history. One in particular I found very interesting so I did some further research and that was the development of synthetic human insulin. First of all insulin is secreated from the pancreas to regulate blood sugar, when the levels are too high you get Diabetes and then when they are too low you get Hypoglycemia.

Then with diabetes there are different levels ( sort of off topic but interesting) depending on how severe the condition is. Anywho people who could not produce enough insulin would need to get their insulin from somewhere else. Back in the 1960-70s and even to this day pig and cow insulin were used as a supplement? They sometime had bad sideffects in patients because they were foreign materials. So scientists got the ideas to create artificial human insulin. They did this by genetically modifiyng the DNA of e.Coli bacteria to produce insulin. In the late 70s to the 80s it was like a race to see who could create it first and Eli Lilly and Company was the first company to commercialize on it and sell it to the public. They also used their technologies to develop and create Humatrope which is used to stimulate growth hormones for people with growth deficiencies. Pretty cool!

Question:
Although the insulin is human insulin why can't the body sense that it has been genetically modified?
If the genetics of a bacteria to produc the insulin wasn't used is it possible to take a human sample of insulin and replicate it, which would be more effective which would-be faster?