Researchers have created a noninvasive way for people with type 1 diabetes to measure blood glucose levels without the pain and inconvenience of pricking a finger.
Researchers at MIT’s Spectroscopy Laboratory are using a technique called Raman spectroscopy that can reveal glucose levels by scanning a patient’s arm or finger with near-infrared light, eliminating the need to draw blood. (Raman spectroscopy is a method that identifies chemical compounds based on the frequency of vibrations of the chemical bonds holding the molecule together.)
Two MIT graduate students, Ishan Barman and Chae-Ryon Kong, are currently developing a small Raman spectroscopy machine about the size of a laptop computer that could be used in a doctor’s office or a patient’s home. Such a devicecould one day help some of the nearly 1 million people in the United States -- and millions worldwide -- who suffer from type 1 diabetes.
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People with type 1 diabetes must keep a careful eye on their blood glucose levels. Too much sugar can damage organs, while too little deprives the body of necessary fuel. Most patients must prick their fingers several times a day to draw blood for testing.
Researchers in the Spectroscopy Lab have been developing this technology for about 15 years. One of the major obstacles they have faced is that near-infrared light penetrates only about half a millimeter below the skin, so it measures the amount of glucose in the fluid that bathes skin cells (known as interstitial fluid), not the amount in the blood. To overcome this, the team came up with an algorithm that relates the two concentrations, allowing them to predict blood glucose levels from the glucose concentration in interstitial fluid.
However, this calibration becomes more difficult immediately after the patient eats or drinks something sugary because blood glucose soars rapidly. Since it takes five to 10 minutes to see a corresponding surge in the interstitial fluid glucose levels, interstitial fluid measurements do not give an accurate picture of what’s happening in the bloodstream.
To address that lag time, Barman and Kong developed a new calibration method, called Dynamic Concentration Correction (DCC), which incorporates the rate at which glucose diffuses from the blood into the interstitial fluid.
In a study of 10 healthy volunteers, the researchers used DCC-calibrated Raman spectroscopy to significantly boost the accuracy of blood glucose measurements — an average improvement of 15 percent, and up to 30 percent in some subjects.
Barman and Kong plan to launch a clinical study to test the DCC algorithm in healthy volunteers this fall.
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