What is the primary difference between Type 1 and Type 2 Diabetes Mellitus?

The primary difference between Type 1 and Type 2 Diabetes Mellitus lies in the underlying mechanisms that lead to hyperglycemia. Type 1 Diabetes is characterized by the autoimmune destruction of pancreatic beta cells, which are responsible for producing insulin. This destruction leads to an absolute deficiency of insulin, often resulting in the need for exogenous insulin administration to manage blood glucose levels.

On the other hand, Type 2 Diabetes is primarily associated with insulin resistance, where the body's cells do not respond effectively to insulin. Initially, this is often accompanied by a compensatory increase in insulin production, but over time, the pancreatic beta cells may become exhausted, leading to insufficient insulin production. This distinction is essential for understanding the different treatment approaches and management strategies for each type of diabetes.

In summary, the correct choice highlights a fundamental biological difference between the two types of diabetes: Type 1's autoimmune pathology versus Type 2's insulin resistance mechanism.