Which disorder is characterized by high blood sugar levels due to the body's inability to produce or respond to insulin?

The disorder characterized by high blood sugar levels due to the body's inability to produce or respond to insulin is diabetes. Diabetes is primarily classified into two main types: Type 1 diabetes, where the pancreas produces little to no insulin, and Type 2 diabetes, where the body becomes resistant to insulin or does not use it effectively. Insulin is a hormone crucial for regulating blood glucose levels; thus, when there is an issue with insulin production or response, glucose cannot be effectively utilized by the body's cells, leading to elevated blood sugar levels.

In contrast, heart disease is a broad term that encompasses various heart-related issues but is not directly tied to insulin production or response. Obesity, while often associated with the development of Type 2 diabetes, does not itself result in high blood sugar due to insulin problems; rather, it is a risk factor for such conditions. Hypertension, or high blood pressure, is also not directly related to insulin's role in blood sugar regulation but might coexist with metabolic disorders like diabetes. This makes diabetes the correct answer, as it specifically pertains to the dysfunction of insulin related to blood glucose management.