Can high blood sugar levels lead to type 2 diabetes?

Yes: Extended exposure to elevated blood sugars can desensitize Insulin receptors in your body, leading to difficulty in blood sugar crossing from the blood stream into the cell. The cells then sense that blood sugars are low inside the cell, thus causing the pancreas to increase Insulin levels to normalize the sugar inside the cell. Over years, this high Insulin state leads to type 2 diabetes.

Type 2 diabetes: High blood sugar levels are the definition of diabetes. Be it type 1 or type 2 diabetes, the result is an inability of the body to regulate blood sugar levels which results in hyperglycemia. Having high blood sugar does not cause diabetes.