A 60-year-old man comes to the office due to progressive blurry vision over the last year that has begun to affect his ability to drive. He has difficulty reading road signs at night and reports excessive glare from the headlights of oncoming cars. The patient has a long history of hypertension and type 2 diabetes mellitus. Funduscopy reveals a diminished red reflex bilaterally with obscuration of retinal detail. It is determined that the patient's condition is in part due to intracellular accumulation of sorbitol. In healthy cells, this sugar alcohol is normally metabolized into which of the following substances to facilitate excretion?

Question

A 60-year-old man comes to the office due to progressive blurry vision over the last year that has begun to affect his ability to drive.  He has difficulty reading road signs at night and reports excessive glare from the headlights of oncoming cars.  The patient has a long history of hypertension and type 2 diabetes mellitus.  Funduscopy reveals a diminished red reflex bilaterally with obscuration of retinal detail.  It is determined that the patient's condition is in part due to intracellular accumulation of sorbitol.  In healthy cells, this sugar alcohol is normally metabolized into which of the following substances to facilitate excretion?

Quizplus · Accepted Answer

Eductional Objective: In the polyol pathway, aldose reductase converts glucose into sorbitol, which is slowly metabolized into fructose by sorbitol dehydrogenase.  Chronic hyperglycemia overwhelms this pathway, causing intracellular sorbitol accumulation and increased osmotic/oxidative stress.  This accelerates cataract development in patients with diabetes, and contributes to the pathogenesis of diabetic retinopathy, neuropathy, and nephropathy.

A 60-Year-Old Man Comes to the Office Due to Progressive