Could diabetes be caused by insulin quality rather than desensitization?
From my rudimentary understanding of diabetes, the theory is that (one type of it) is caused by the cells who respond to insulin becoming desensitized to the insulin and having a weaker response to it. Although this theory makes sense, I find it a little hard to believe that untold numbers of cells in the body have their response to insulin weakened, as opposed to perhaps the insulin quality being worse.
I know that insulin is cleaved from pro-insulin by an enzyme, but what if the glycation of that enzyme makes it less capable of cleaving insulin? What if the glycation of other proteins involved in the transport of insulin outside of the beta-pancreatic cells causes its quality to be degraded? It could also explain why diabetes does not get cured as the blood sugar after a person eats would remain high as it passes from the stomach through the pancreas before getting filtered by the liver or dispersing throughout the rest of the body, so if glycation degrades the insulin or proteins involved in its transport, that could be an alternative mechanism for the onset of diabetes.