The back diffusion of glucose across human skin in vitro.

For diabetic patients, blood glucose monitoring is an important part in the management of their disease, however the acquisition of blood requires the use of invasive and often painful methods, and the development of a technique that removes these problems would represent a major advance. The uppermost membrane of the skin, the stratum corneum, has been shown to be the main barrier to percutaneous absorption, but there have been claims that polar water-soluble compounds diffuse across it via aqueous pathways. In this study, skin diffusion cells were used to investigate the back diffusion of tritiated water and the convective transport of 3H-glucose across full thickness human skin after the application of a number of different materials to the stratum corneum. Significant amounts of 3H-glucose back diffused only after complete removal of the stratum corneum by tape stripping, and it is likely that any future attempts to monitor blood glucose levels using non-physical techniques will require a certain degree of damage to the stratum corneum. The extraction through the skin of tritiated water and 3H-glucose after the application of solutions with different osmotic pressures were consistent with the theory that solutions with high osmotic pressures dehydrate the stratum corneum which suggests that passive transport of these radiolabelled molecules through porous pathways was insignificant.