Glucose, transport through membranes

If insulin acts by facilitating glucose transport through the cell membrane, the mode of action of insulin must be studied at a level of integration other than the one at which a hormone acts directly on an enzyme. 

The kinetics of glucose transport through the membrane follows the Michaelis-Menten equation ... 

Special carrier molecules exist for certain substances that are important for cell function and too large or too insoluble in lipid to diffuse passively through membranes, eg, peptides, amino acids, glucose. These carriers bring about movement by active transport or facilitated diffusion and, unlike passive diffusion, are saturable and inhibitable. Because many drugs are or resemble such naturally occurring peptides, amino acids, or sugars, they can use these carriers to cross membranes. 

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