Comparison of carbohydrate utilization in man using indirect calorimetry and mass spectrometry after an oral load of 100 g naturally-labelled [13C]glucose.
1. Carbohydrate (CHO) oxidation was measured simultaneously in a group of five normal subjects after an oral load of 100 g naturally-labelled [13C]glucose, using indirect calorimetry and mass spectrometry. 2. CHO utilization, calculated from the results of indirect calorimetry, increased 30 min after the glucose load to reach a peak at 90 min. It then decreased to reach basal values at 380 min. Cumulative total CHO oxidation at 480 min was 83 +/- 8 g, and CHO oxidized above basal levels, 37 +/- 3 g. 3. Enrichment of expired carbon dioxide with 13C began at 60 min and maximum values were observed at 270 min. At 480 min, cumulative CHO oxidation measured by use of [13C]glucose was 29 g. The difference from calorimetric values can be attributed in part to the slow isotopic dilution in the glucose and bicarbonate pools. 4. Thus, approximately 30% of the glucose load was oxidized during the 8 h after its ingestion and this accounts for a significant part of the increased CHO oxidation (37 g), as measured by indirect calorimetry.
D000293:Adolescent; D000328:Adult; D001786:Blood Glucose; D002151:Calorimetry; D050260:Carbohydrate Metabolism; D004040:Dietary Carbohydrates / Q000378:metabolism; D004734:Energy Metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D013058:Mass Spectrometry; D010084:Oxidation-Reduction
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D005947:Glucose