 Aldose reductase activity increases as the glucose concentration rises in diabetes in those tissues that are not insulin sensitive, which include the lenses, peripheral nerves and glomerulus.Sorbitol does not diffuse through cell membranes easily and therefore accumulates, causing osmotic damage which leads to retinopathy and neuropathy.Natural sources reported to inhibit aldose reductase include indian gooseberry, spinach, cumin seeds, fennel seeds, basil leaves, lemon, black pepper, orange, curry leaves, cannabis, cinnamon and lichen.