NIR Light in Smartwatches Could Provide Noninvasive Blood Glucose Monitoring

Blood glucose measurements (BGL) measurements typically involve drawing blood through a finger prick, but researchers want to leverage modern electronics to develop less painful and noninvasive alternatives. In a new study, published in the Journal of Biomedical Optics, a research team turns to near-infrared light (NIR) measurements to estimate BGL.

The team began by extracting oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb) signals from NIR measurements. By analyzing this data, they determined that the phase delay between the low-frequency and oscillating components of HbO2 and Hb signals are closely linked to the degree of oxygen consumption during each cardiac cycle—an important metabolism indicator.

To test their newfound metabolic index, researchers placed an NIR sensor from a smartwatch over the finger of healthy participants at rest. The participants then consumed different sugary and sugar-free beverages, allowing the team to measure blood glucose changes. Excitingly, the changes in metabolic index matched variations in blood glucose as measured by a commercial continuous glucose monitor.