Researchers have a developed a new laser device that could allow diabetic patients to check their blood sugar level without pricking themselves to draw blood.

The researchers from Princeton University described that they measured blood sugar by directing their specialized laser at a person's palm. The laser passes through the skin cells, without causing damage, and was partially absorbed by the sugar molecules in the patient's body. The researchers use the amount of absorption to measure the level of blood sugar.

Sabbir Liakat, said that the glucose monitors are required to produce a blood-sugar reading within 20 percent of the patient's actual level and even an early version of the system met that standard because the current version was 84 percent accurate.

The key to the system was the infrared laser's frequency. What our eyes perceive as color was created by light's frequency. Red would be the lowest frequency of light that humans normally can see, and infrared's frequency was below that level. Current medical devices often use the "near-infrared". This frequency was not blocked by water, so it can be used in the body. But it does interact with many acids and chemicals in the skin, so it makes it impractical to use for detecting blood sugar.

Mid-infrared light, however, was not as much affected by these other chemicals, so it works well for blood sugar. But mid-infrared light was difficult to harness with standard lasers. It also required relatively high power and stability to penetrate the skin and scatter off bodily fluid.

The researchers said their results indicated that the laser measurements readings produced average errors somewhat larger than the standard blood sugar monitors, but remained within the clinical requirement for accuracy.

The study is published in the journal Biomedical Optics Express.