In most people with high blood sugars, two things are happening.
First, the liver is overproducing glucose, dumping large amounts of it into the blood circulation.
Secondly, the glucose is not entering the cells easily, and more of it is staying in the circulation.
Both of these abnormalities result in high blood glucoses, because the insulin present is inadequate, either in amount, or in its action, or both. In other words, insulin should help move glucose into cells, and cut down glucose production by the liver, but this is not happening.
In people with Type 2 diabetes, the insulin does not work as well as it should in these tasks, and blood glucose rises. This is what doctors refer to as a state of insulin resistance. The body is relatively "resistant" to the action of insulin and requires more of it than usual to accomplish the tasks. Indeed, if your body were able to produce enough insulin to overcome this state of insulin resistance, your blood glucose would be normal. Unfortunately, in the individual with Diabetes, less than usual amounts are present, so glucose rises.