I started with a question: Is there an agreement that insulin resistance is involved in type 2 diabetes? I just wanted to know what the popular websites that people would be researching type 2 diabetes would be saying about the causes (etiology) of this disease. What I found was there is generally a hypothesis that type 2 diabetes being caused by either insulin resistance or a failure of the pancreas to produce sufficient insulin. I would suggest that these are different metabolic states, perhaps distinct or perhaps related etiologies. If we accept that the progression is from insulin resistance to lowered insulin output, at least in a large subset of people with type 2 diabetes, then treating insulin resistance should be the focus, not low insulin and not high blood sugar. But all of this is better explained by Dr. Jason Fung. Here are the quotes I found about the causes of Type 2 Diabetes:

From WebMD:

people with type 2 diabetes produce insulin; however, the insulin their pancreas secretes is either not enough or the body is unable to recognize the insulin and use it properly (insulin resistance).

From the Mayo Clinic:

Type 2 diabetes develops when the body becomes resistant to insulin or when the pancreas stops producing enough insulin. Exactly why this happens is unknown…

From the American Diabetes Association:

If you have type 2 diabetes your body does not use insulin properly. This is called insulin resistance. At first, your pancreas makes extra insulin to make up for it. But, over time it isn’t able to keep up and can’t make enough insulin to keep your blood glucose at normal levels.

Type 2 diabetes occurs when the pancreas doesn’t produce enough insulin to maintain a normal blood glucose level, or the body is unable to use the insulin that is produced – known as insulin resistance.