What is diabetes primarily characterized by?

Diabetes is primarily characterized by high levels of blood glucose, also known as hyperglycemia. This condition occurs because the body either does not produce enough insulin, a hormone that regulates blood sugar, or the cells become resistant to insulin's effects. As a result, glucose, which is the body's main source of energy, accumulates in the bloodstream instead of being utilized by the cells. Over time, uncontrolled high blood sugar can lead to serious complications affecting various organs and systems, including the heart, kidneys, eyes, and nerves. Understanding this fundamental aspect of diabetes is crucial for managing the condition and preventing complications. The other options presented do not accurately describe the main feature of diabetes.