**Core Concept**
Diabetes mellitus, corticosteroid use, and certain genetic disorders are known to increase the risk of cataract formation. Cataracts are characterized by the opacification of the lens in the eye, leading to vision impairment.

**Why the Correct Answer is Right**
Cataracts are a common complication of diabetes mellitus, particularly in patients with long-standing disease. The exact mechanism is not fully understood, but it is thought to be related to the accumulation of sorbitol in the lens due to the action of aldose reductase. This leads to osmotic changes and ultimately, the formation of cataracts. Corticosteroid use can also lead to cataract formation, particularly posterior subcapsular cataracts, due to its effects on the lens epithelial cells.

**Why Each Wrong Option is Incorrect**
**Option A:** While diabetes mellitus is a well-known risk factor for cataract formation, option A is not the correct answer.
**Option B:** Corticosteroid use is also a known risk factor for cataract formation, so option B is not the correct answer.
**Option D:** Certain genetic disorders, such as Down syndrome, are also associated with an increased risk of cataract formation.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that patients with diabetes mellitus should have regular eye exams to monitor for cataract formation and other eye complications.

**Correct Answer:** None