Near-infrared spectroscopic sensing of important metabolic biomarkers for people with type I diabetes

The next-generation artificial pancreas is under development with the goal to enhance tight glycemic control for people with type 1 diabetes. Such technology requires the integration of a chemical sensing unit combined with an insulin infusion device controlled by an algorithm capable of autonomous operation. This work explores the potential of near-infrared spectroscopic sensing to serve as the chemical sensing unit.

Independent measurements of glucose, β-hydroxybutyrate and urea in ternary aqueous solutions are demonstrated using near-infrared spectroscopy coupled with multivariate data analysis techniques. Key analytical parameters, including sensitivity and selectivity, are determined for each analyte. Multiple data analysis methods are demonstrated to be capable of providing accurate concentrations for these metabolic biomarkers. The measurement quality is sufficient for monitoring physiological levels of glucose and urea in samples of interstitial fluid and for the detection of diabetic ketoacidosis.

Noninvasive glucose measurements in human subjects with type 1 diabetes are demonstrated via analysis of near-infrared spectra collected on the back of the subject’s hand. Glucose levels in the interstitial fluid, rather than in capillary blood, are demonstrated to be better suited as reference glucose concentrations for near-infrared spectroscopic sensing. Variations in non-glucose information embedded in the near-infrared spectra are investigated, providing a basis for identification and rejection of spectral outliers, thereby providing a method to improve clinical accuracy of the noninvasive measurements.