Noninvasive glucose monitoring by back diffusion via skin: chemical and physical enhancements.

Blood glucose levels are routinely obtained by invasive and painful methods using glucose meters and test strips. The development of less invasive or non invasive techniques would be beneficial for diabetes patients. In this study, a noninvasive method was evaluated using the back diffusion of glucose across skin with or without permeation enhancement methods. An in vitro model was utilized. The stratum corneum (SC) was the predominant barrier for both back and forward diffusion of glucose across skin. Surfactants with various charges and essential oils (cyclic monoterpenes) were used as chemical enhancers to promote the back diffusion of glucose. A cationic surfactant (benzalkonium chloride) showed the highest enhancement, followed by anionic and nonionic surfactants. d-Limonene and 1,8-cineole dispersed in appropriate proportions of ethanol could enhance the glucose diffusion after pretreatment of the skin surface. Electroporation, defined as a physical method, significantly increased the amount of glucose that diffused back. The percentages of diffused glucose by 300 V (volts) and 500 V high voltage pulses on skin for 10 min were found to be 45 and 75 times greater than the control group, respectively.