Polyol pathway

When glucose is unused, it is metabolized via the polyol pathway. This pathway consists of two main enzymatic steps. First, glucose is reduced to sorbitol by aldose reductase. In this step, NADPH is oxidized to NADP+. The next step is the oxidation of sorbitol to D-fructose by sorbitol dehydrogenase. Fructose can then be phosphorylated by fructokinase and subsequently be metabolized via dihydroxyacetone phosphate or glyceraldehyde to D-glyceraldehyde 3-phosphate, which can be used as a substrate in the process of glycolysis. The sorbitol pathway plays a role in diabetic renal complications because aldose reductase metabolizes the excess of glucose to toxic metabolites that induce hyperfiltration and glomerular dysfunction.

当葡萄糖未被利用时，将通过多醇途径进行代谢。该途径主要由两个主要的酶促步骤组成。首先，葡萄糖在醛糖还原酶的作用下被还原为山梨醇。在此过程中，NADPH被氧化为NADP+。接下来的步骤是山梨醇在山梨醇脱氢酶的催化下被氧化为D-果糖。随后，果糖可以被果糖激酶磷酸化，进而通过二羟丙酮磷酸或甘油醛进行代谢，最终转化为D-甘油醛-3-磷酸，该物质可作为糖酵解过程中的底物。山梨醇途径在糖尿病肾并发症中发挥重要作用，因为醛糖还原酶将葡萄糖的过量代谢为有毒代谢产物，这些产物可引起滤过增加和肾小球功能障碍。