title: Transcutaneous glucose measurement using near-infrared spectroscopy during hypoglycemia.
abstract: OBJECTIVE
  To analyze a transcutaneous near-infrared spectroscopy system as a technique for in vivo noninvasive blood glucose monitoring during euglycemia and hypoglycemia.
  
  
  METHODS
  Ten nondiabetic subjects and two patients with type 1 diabetes were examined in a total of 27 studies. In each study, the subject's plasma glucose was lowered to a hypoglycemia level (approximately 55 mg/dl) followed by recovery to a glycemic level of approximately 115 mg/dl using an intravenous infusion of insulin and 20% dextrose. Plasma glucose levels were determined at 5-min intervals by standard glucose oxidase method and simultaneously by a near-infrared spectroscopic system. The plasma glucose measured by the standard method was used to create a calibration model that could predict glucose levels from the near-infrared spectral data. The two data sets were correlated during the decline and recovery in plasma glucose, within 10 mg/dl plasma glucose ranges, and were examined using the Clarke Error Grid Analysis.
  
  
  RESULTS
  Two sets of 1,704 plasma glucose determinations were examined. The near-infrared predictions during the fall and recovery in plasma glucose were highly correlated (r = 0.96 and 0.95, respectively). When analyzed during 10 mg/dl plasma glucose segments, the mean absolute difference between the near-infrared spectroscopy method and the chemometric reference ranged from 3.3 to 4.4 mg/dl in the nondiabetic subjects and from 2.6 to 3.8 mg/dl in the patients with type 1 diabetes. Using the Error Grid Analysis, 97.7% of all the near-infrared predictions were assigned to the A-zone.
  
  
  CONCLUSIONS
  Our findings suggest that the near-infrared spectroscopy method can accurately predict plasma glucose levels during euglycemia and hypoglycemia in humans.
authors.affiliation: Department of Medicine (Division of Endocrinology and Metabolism), Albert Einstein College of Medicine, Bronx, New York 10461, USA.
authors.forename: I
authors.initials: I
authors.lastname: Gabriely
authors.forename: R
authors.initials: R
authors.lastname: Wozniak
authors.forename: M
authors.initials: M
authors.lastname: Mevorach
authors.forename: J
authors.initials: J
authors.lastname: Kaplan
authors.forename: Y
authors.initials: Y
authors.lastname: Aharon
authors.forename: H
authors.initials: H
authors.lastname: Shamoon
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis*; D015992:Body Mass Index; D002138:Calibration; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000150:complications; D005260:Female; D006801:Humans; D007003:Hypoglycemia / Q000097:blood / Q000175:diagnosis*; D008297:Male; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D001786:Blood Glucose