carbohydrate metabolic pathway glucose reduction pathway polyol pathway 2014-03-20T09:06:03Z PW:0001518 PW:0001520 The polyol pathway is triggered by excess glucose which is reduced to sorbitol in the first step which requires NADPH as a cofactor. Sorbitol is eventually converted to fructose. Sorbitol, which is membrane impermeable and metabolites of fructose which can lead to the production of AGEs (advance glycation endproduct), along with other pathways affected by a hyperglycemic state are thought to be associated with the pathophysiology of diabetic retinopathy. The intermediate sorbitol in the pathway is a sugar alcohol; sugar alcohols are a class of polyols - alcohol molecules with multiple hydroxyl groups. pathway sorbitol-aldose reductase pathway vpetri