title: Glucose naturally labeled with carbon-13: use for metabolic studies in man.
abstract: The ratio of carbon-13 to carbon-12 is much higher in most commerical preparations of glucose used for oral glucose tolerance tests than it is in carbon dioxide in expired air. This recent discovery provided a novel and potentially significant means of studying glucose metabolism. The changes in the ratio of carbon-13 to carbon-12 in carbon dioxide expired after oral glucose administration were determined by mass spectrometry. In six healthy male volunteers, the administration of glucose resulted in a marked, reproducible rise in the isotopic ratio in expired carbon dioxide; the ratio reached its maximum at 4 hours and then declined progressively.
mesh_terms: D000328:Adult; D001786:Blood Glucose; D002247:Carbon Isotopes; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005947:Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D012119:Respiration; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D002247:Carbon Isotopes; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D005947:Glucose