Diabetes testing, or lack thereof

I was diagnosed with diabetes in 2010. No real tests were ever done, just a simple finger prick that showed my sugar level was 455. I can accept that I'm diabetic. I have made changes in my life to accommodate and try to learn to live with it.

What I find puzzling and really unacceptable is that I have never received an answer to the question: What caused me to BE diabetic? I understand that my body isn't processing sugar correctly and that is the end result of what caused me to be diabetic, but why isn't it processing sugar? The treatment plans that doctors have would seem to dictate that you had to know the answer to this question, but no one has ever bothered to test me to see.

I was told there are two body functions that are not happening that would cause you to be diabetic. And I've been told it's one or the other, never both. I don't know if this is right. I don't think it is. I was told either your body isn't producing insulin or your body isn't using insulin, which resulted in your being diabetic. But how do you know which it is? Could it be both? And don't you really need to know which it is so you know if you need to be taking insulin or something to open the insulin receptors on your cells? Cause if you aren't making insulin, it seems to me that no matter how many insulin receptors you have open, it won't make a difference because there is nothing there to be received. At the same time, if you are making insulin but not using it, it doesn't matter if you take more insulin, your body is going to just ignore it and not use it.

So why then, do doctors dig in and refuse to test you to see if you need insulin or need to open the insulin receptors? Why do doctors refuse to test to see why you aren't producing insulin or why you aren't using insulin? What if, there was something else that was causing you to not produce or use insulin and if you fixed that other, underlying cause, you would not be diabetic? Is it that much easier (and more profitable) to simply say, you're diabetic so I'm going to blindly prescribe this and see if it works? That doesn't seem to be a very smart way to go about doing things to me.