In poorly controlled diabetes mellitus, cataracts develop early because excess glucose entering the lens is converted to sorbitol by aldose reductase using NADPH as cofactor. Accumulation of intracellular sorbitol causes osmotic swelling of lens fibers. Which other tissue develops clinical damage through this same polyol pathway?

• A Skeletal muscle
• B Adrenal cortex
• C Hepatocytes
• D Schwann cells of peripheral nerves ✓

Explanation

The polyol (sorbitol) pathway converts glucose to sorbitol via aldose reductase and then to fructose via sorbitol dehydrogenase. Tissues lacking high sorbitol dehydrogenase activity, such as lens, retina, kidney, and Schwann cells, accumulate sorbitol, producing osmotic stress. This contributes to diabetic cataracts and peripheral neuropathy. Aldose reductase uses NADPH, so it competes with glutathione reductase and worsens oxidative injury in these tissues.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.