What are the two primary types of diabetes mellitus?

The two primary types of diabetes mellitus are Type 1 and Type 2 diabetes. Type 1 diabetes is characterized by the autoimmune destruction of insulin-producing beta cells in the pancreas, leading to an absolute insulin deficiency. This type is often diagnosed in childhood or adolescence, although it can occur at any age. Patients with Type 1 diabetes require lifelong insulin therapy to manage their blood glucose levels.

Type 2 diabetes, on the other hand, typically develops in adults and is associated with insulin resistance, where the body's cells do not respond adequately to insulin, combined with a relative insulin deficiency. Management of Type 2 diabetes often includes lifestyle modifications such as diet and exercise, and it may require medications or insulin as the disease progresses.

The other options listed refer to variations or less common forms of diabetes, with Type 3 not being recognized as a primary type and the types indicated in choices regarding letters or numbers not adhering to the established classification of diabetes. Understanding that Type 1 and Type 2 are the foundational categories of diabetes mellitus is essential for effective diagnosis and management in clinical practice.