# Sorbitol (Polyol) Pathway

The **Sorbitol Pathway**, also called the **Polyol Pathway**, is a two-step process that converts glucose to fructose. The pathway contributes to **diabetic complications** affecting the eyes, kidneys, and nerves.

First, **glucose** is converted **into sorbitol**, in a reaction catalyzed by **aldose reductase**. This reaction also **uses NADPH**, producing NADP+ in the process.

Second, **sorbitol** is converted **into fructose** by **sorbitol dehydrogenase**. This reaction **produces NADH** from NAD+ in the process.

Deficiencies in sorbitol dehydrogenase activity cause **sorbitol accumulation** in high glucose states, such as in **diabetes mellitus**. The major tissues with poor sorbitol dehydrogenase activity are the **lens**, **retina**, **kidney**, and **schwann cells** of the peripheral nervous system. Sorbitol accumulation contributes to **cataracts**, **retinopathy**, **renal failure**, and **peripheral neuropathy**, respectively.

Find this Sorbitol (Polyol) Pathway mnemonic and more [Biochemical Pathways](/content/browse#playlist-4028/index.html) mnemonics among Pixorize's visual mnemonics for the USMLE Step 1 and NBME Shelf Exams.