Which species has a lower incidence of diabetic cataracts due to reduced aldose reductase activity?

Which species has a lower incidence of diabetic cataracts due to reduced aldose reductase activity?

• A. Dogs
• B. Cats (correct)
• C. Horses
• D. Rabbits

Answer: (B)

When glucose levels rise in diabetes, the lens can shuttle glucose into the polyol pathway via aldose reductase, converting it to sorbitol. Sorbitol inside the lens draws water osmotically, causing swelling of lens fibers and progressive cloudiness known as a diabetic cataract. The extent of this damage depends on how active aldose reductase is in the lens. If this enzyme activity is reduced, less sorbitol forms, and the osmotic stress is smaller, so cataract formation is less likely. Cats have relatively low aldose reductase activity in the lens, which explains their lower incidence of diabetic cataracts compared with species that have higher activity. In contrast, species with higher lens aldose reductase activity tend to accumulate more sorbitol under hyperglycemia and are more prone to cataracts.

When glucose levels rise in diabetes, the lens can shuttle glucose into the polyol pathway via aldose reductase, converting it to sorbitol. Sorbitol inside the lens draws water osmotically, causing swelling of lens fibers and progressive cloudiness known as a diabetic cataract. The extent of this damage depends on how active aldose reductase is in the lens. If this enzyme activity is reduced, less sorbitol forms, and the osmotic stress is smaller, so cataract formation is less likely. Cats have relatively low aldose reductase activity in the lens, which explains their lower incidence of diabetic cataracts compared with species that have higher activity. In contrast, species with higher lens aldose reductase activity tend to accumulate more sorbitol under hyperglycemia and are more prone to cataracts.