Cataract in diabetes is caused by
B. i.e. (Sorbitol) (186 - Harper 27th) (280- U-satyanarayan 3rd)Sorbitol Pathway in Diabetes MellitusIn uncontrolled diabetes (hyperglycemia) large amounts of glucose enter the cells which are not dependent on insulin. Significantly the cells with increased intracellular glucose levels in diabetes (lens, retina, nerve cells, Kidney etc) possess high activity of aldolase reductase, and sufficient supply of NADPH. This results in a rapid and efficient conversion of glucose to sorbitol. The enzyme sorbitol dehydrogenase however is eithr low in activity or absent in these cells, hense sorbitol is not converted to fructose. Sorbitol cannot freely pass through the cell membrane, and accumulate in the cells where it is produced. Sorbitol due to its hydrophilic nature- causes strong osmotic effects leading to swelling of the cells. Some of the pathological changes associated with diabetes (like Cataract formation, peripheral neuropathy, nephropathy) are believed to be due to the accumation of sorbitol)* Cataract in a diabetic is caused by sorbitol which is formed by interaction on glucose by - Aldolase reductase*** Essential fructosuria - due to deficiency of enzyme fructokinae** Hereditary fructose intolerance- is due to absence of enzyme - aldolase - B*** Essential pentosuria - deficiency of xylitol- dehydrogenase**
Glucose
Sorbitol
Fructose
Sucrose
Carbohydrates