Our bodies need insulin.
With type 1, our body has decided to destroy all the cells that create insulin. Therefore, we have to provide it with the insulin it requires.
Unfortunately, digestive acids destroy insulin which is why it is not taken in oral form.
When we are first diagnosed with type 1, there are likely to be some insulin producing cells still left within our body. We call this the "honeymoon period". Unfortunately, our body finally gets around to destroying them too. There has been some research into prolonging the honeymoon period but I am not aware of any that has managed to prolong this period for ever.
There have been some attempts to transplant insulin producing cells which have been met with differing levels of success but all require heaps of anti-rejection drugs after very serious surgery.
There are methods to reduce the amount of insulin you need such as reducing carbs and increasing exercise.
But why are you asking? Do you have a problem with taking insulin.