What characterizes diabetes mellitus?

Diabetes mellitus is primarily characterized by hyperglycemia, which refers to elevated levels of glucose in the blood. This condition arises from defects in insulin secretion, insulin action, or both. In individuals with diabetes, the body's ability to produce or respond to insulin effectively is compromised.

In Type 1 diabetes, an autoimmune destruction of pancreatic beta cells leads to insufficient insulin production. In Type 2 diabetes, insulin resistance develops, where the body's cells do not respond effectively to insulin, coupled with impaired insulin production over time. As a result, the glucose that normally would be taken up by cells and used for energy remains in the bloodstream, causing hyperglycemia.

Understanding this mechanism highlights why the answer regarding hyperglycemia due to insulin-related defects is the most accurate characterization of diabetes mellitus. The other options, such as excessive insulin production or inability to utilize lipids, do not accurately represent the condition of diabetes and normal blood sugar levels contradict the very definition of diabetes mellitus.