Just a word of caution though in addition to the above. Having autoimmune diabetes doesn’t preclude you from potentially developing resistance later in life. If one lives a life of eating doughnuts washed down with sugary drinks, they are just as likely to develop insulin resistance as anyone else, irrespective of whether their insulin comes from a needle or their pancreas.
Obviously that’s an extreme example and I’m not for a moment offering any dietary advice, but rather just putting it out there that it’s perhaps not the best idea to assume you can eat whatever you like and cover it with insulin. Certainly not over the course of decades. At its core this is no different to the mechanism that brings about T2DM in normal people.