As of 2015, a laser tests glucose levels by penetrating the palm and striking sugar molecules, which then absorb part of the beam, explains Medical News Today. Unlike traditional glucose meters, which measure sugar levels in blood, the laser measures sugar in something called dermal interstitial fluid, which is the fluid between cells.
The laser uses a beam in the middle range of infrared light that doesn't react to other chemicals in the skin, says Medical News Today. A laser using this wavelength needs more power and greater stability in order to penetrate the skin. A new type of laser called a quantum cascade laser provides the stability and power required. Initially, the laser required an elaborate cooling system, but now it works at room temperature. However, the device is still too large for home use.
Traditional glucose meters are required to be at least 80 percent accurate, and the most recent version of the laser is 84 percent accurate, notes Medical News Today. An initial study of three subjects revealed that the laser's average readings were not as accurate as a standard glucose meter, but they were within the acceptable range. The use of this new type of laser for medical applications may not be limited to testing glucose levels.