**Core Concept**
Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease characterized by the selective destruction of pancreatic beta cells, leading to insulin deficiency and hyperglycemia. This condition is distinct from type 2 diabetes, which is often associated with insulin resistance and impaired insulin secretion.

**Why the Correct Answer is Right**
The pathogenesis of T1DM involves the activation of autoreactive T cells, which recognize and destroy beta cells in the islets of Langerhans. This process is mediated by the production of autoantibodies against insulin, glutamic acid decarboxylase (GAD), and other beta-cell antigens. The resulting insulin deficiency necessitates exogenous insulin administration to maintain glucose homeostasis.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect, as T1DM is not caused by a lack of insulin receptors on peripheral tissues.
**Option B:** Incorrect, as T1DM is characterized by insulin deficiency, not insulin resistance.
**Option C:** Incorrect, as T1DM is an autoimmune disease, not a result of viral infections.

**Clinical Pearl / High-Yield Fact**
T1DM typically presents in children and young adults, with a strong genetic predisposition and a potential association with other autoimmune diseases, such as thyroiditis and celiac disease.

**Correct Answer:** B. T1DM is characterized by insulin deficiency, not insulin resistance.