Jinsh

Both monosaccharide and disaccharides traverse the walls of blood and lymph capillaries serious cavities freely by a simple process of diffusion. Their concentrations throughout the extracellular fluid are, therefore, uniform except as the equilibrium may be disturbed in local areas by exchanges of monosaccharide with cells. They traverse the glomerular filter with the same freedom.

From the cells, on the other hand, disaccharides are entirely excluded. The cells of the mammary gland my appear to be an exception to this rule;  but lactose is actually formed in the cells of this gland from glucose or its products and is prevented from escaping into the extracellular fluid and the blood stream unless, from lack of normal drainage  through the nipple, the pressure in the breast becomes excessive.

Monosaccharide’s cross cellular membranes, not by simple diffusion, but by chemical reactions presumably requiring expenditure of energy end activity of enzymes. In fact, the majority of cells in the body seem to contain no free monosaccharide; the carbohydrate in them is entirely glycogen or esters.