IR technology has been the most active area in non-invasive monitoring research. A lot of excitement was generated by this technology many years ago when it was found IR waves could directly measure glucose.
Devices were developed that could measure the ripeness of fruit indicated by the glucose content in their skins by reflecting infrared waves off the fruit. Approaches to measuring glucose in the body are now being attempted using both near and middle infrared waves are being utilized. IR waves have shorter wavelengths and are closer to visible light than radio waves.
But problems arose when through-the-skin measurements were attempted due to the marked scattering and poor transmission of IR waves compared to radio waves. The longer radio frequencies from a distant radio station can pass right through the roof and walls of a house to light up the sound in your radio.
But the shorter frequency IR waves found in sunlight are easily stopped by the same roof and walls. A similar situation exists when attempting to measure glucose inside the body. Radio waves, which cannot directly measure glucose, are easy to transmit, while IR waves, which can directly measure glucose, are poorly transmitted and scatter easily.
Many approaches to overcoming the transmission problem are being attempted, such as using sophisticated equipment to generate stronger IR waves using laser technology for transmission through a finger or other body part, and also by shortening the path of transmission, although this usually necessitates minor surgery such as that used by Animas. Equipment costs for external IR sensors are higher, and larger devices are necessitated by the inherently low transmission rate of IR waves through a finger or arm.
Luckily, the U.S. military has been interested in this technology for military reasons and some of their solutions may benefit those with diabetes. The military helped in the development of a sensitive IR sensor, called a Fabry-Perot sensor that improves sensitivity and may assist companies in developing IR glucose-sensing technology. Some of the companies involved in developing this technology are listed above.