Before There Was Insulin How Did They Cure Diabetes?

There was no cure back then and no cure now. Insulin just helps to prevent it and the person who has it is going to lead a life of sorrowness by not being able to eat certain things, be restricted, having to inject themselves and stuff like that.

They used to just try to have you live as long as possible. The point of medicine is to either a)cure b) keep alive.

So, you've actually given the answer to your own question. People did just die, except they died much horribly than they do now. They had parts of their body amputated and some do now, but its mostly in countries that cannot afford insulin.

Diabetes is similar to cancer or AIDs, they don't have cures, but they have medicines to prevent or prolong your life for good or bad.

"The purpose of insulin itself is to control blood glucose levels when other medications become insufficent." -Wikipedia