For diabetics keeping tabs on their blood sugar level, life is punctuated with painful needle sticks. A study by chemists Gary Small of Ohio University and Mark Arnold of the University of Iowa gives the promise of the first noninvasive test. The researchers shone infrared light onto the tongues of volunteers and measured how much came out the other side of this blood-rich appendage, noting a correlation between blood glucose level and the amount of the infrared light absorbed. Developing a practical home instrument is next. Small says a $500 monitor the size of a portable CD player that targets the ear lobe could be available in three to five years.