**Core Concept**
Glucocorticoids are a class of steroid hormones that play a crucial role in regulating inflammation, immune response, and metabolism. They exert their effects by binding to the glucocorticoid receptor, which then translocates to the nucleus to modulate gene expression.

**Why the Correct Answer is Right**
Glucocorticoids have anti-inflammatory and immunosuppressive properties, making them useful in the treatment of various conditions such as asthma, rheumatoid arthritis, and severe allergic reactions. They work by inhibiting the production of pro-inflammatory cytokines, reducing inflammation, and stabilizing mast cells. The mechanism of action involves the inhibition of phospholipase A2, lipoxygenase, and cyclooxygenase enzymes, which are involved in the synthesis of eicosanoids. This results in a decrease in the production of prostaglandins, leukotrienes, and thromboxanes, which are key mediators of inflammation.

**Why Each Wrong Option is Incorrect**
**Option A:** Glucocorticoids are not typically used to treat infections such as tuberculosis, as they can suppress the immune system and worsen the infection.
**Option B:** While glucocorticoids can have some effects on blood sugar levels, they are not typically used to treat diabetes mellitus.
**Option C:** Glucocorticoids are not used to treat conditions such as hypertension, as they can actually increase blood pressure.

**Clinical Pearl / High-Yield Fact**
Glucocorticoids can cause adrenal suppression, a condition where the adrenal glands are unable to produce sufficient cortisol, leading to symptoms such as fatigue, weight loss, and hypotension. This is a critical consideration when using glucocorticoids for prolonged periods.

**Correct Answer:** C. Severe allergic reactions.