Aldose reductase inhibitors (ARIs) are an experimental class of medications that inhibit an enzyme (protein that produces chemical reactions in the body) called aldose reductase. This enzyme normally increases the rate at which aldoses (types of sugars) are reduced to sorbitol, a sugar alcohol. Sorbitol can cause problems for people with diabetes, who are vulnerable to high glucose (blood sugar).

When too much sorbitol becomes trapped in the eye or nerve cells, it can cause cataracts (clouding of the eye lens) or damage nerve cells in the eyes of people with diabetes. This can cause an eye disorder known as diabetic retinopathy. Excess sorbitol may also be involved in a common nerve disease known as diabetic neuropathy and a common kidney disease called diabetic nephropathy.

Aldose reductase inhibitors are being studied as a potential treatment to prevent or control damage to the eyes, nerves and kidneys in people with diabetes.