Type 2 diabetes mellitus is primarily characterized by which condition?

Type 2 diabetes mellitus is primarily characterized by a disorder of insulin resistance with eventual insulin deficiency. In this condition, the body's cells become less responsive to insulin, which is the hormone responsible for allowing glucose to enter cells for energy. As a result, the body needs more insulin to have the same effect on glucose metabolism. Over time, the pancreas cannot keep up with the increased demand for insulin and begins to fail, leading to further glucose intolerance and hyperglycemia.

This progressive nature of insulin resistance and the subsequent decline in insulin production is what distinguishes type 2 diabetes from other forms of diabetes, such as type 1 diabetes, which is characterized primarily by autoimmune destruction of the insulin-producing beta cells in the pancreas. Additionally, while environmental factors and lifestyle choices play a significant role in the development of type 2 diabetes, it is the combination of insulin resistance and the eventual insulin deficiency that fundamentally defines the condition.

In summary, the characteristic insulin resistance coupled with the progressive decline in insulin secretion is what defines type 2 diabetes mellitus, making this answer the most accurate representation of the condition.